Get in touch

What is Unreasonable Behaviour in a Divorce?

Due to changes in the UK law we have now moved to a ‘no-fault’ divorce system which came into effect in April 2022. View our full guide to no-fault divorce.

Unreasonable behaviour was the most common ground for divorce in England and Wales. To establish ‘unreasonable behaviour’, the petitioner needs to show that their spouse has behaved in such a way that they could not reasonably be expected to live with them anymore.

We previously examined if it is reasonable to question unreasonable behaviour in a divorce and further examined a recent ruling of the court of appeal which refused to allow a woman to divorce her husband because of his ‘unreasonable behaviour’.  No doubt this is a topical area of divorce law.

Going through a divorce is one of the biggest upheavals many of us will face in our lifetimes. As solicitors, we spend a lot of our time and focus on the financial aspect of the divorce process because the financial settlement is often the element that takes the longest to resolve.

When a celebrity or high net worth individual divorce ‘battle’ is reported in the media, it is usually related to how their assets will be divided upon divorce which can make the divorce process seem so lengthy.

Before getting into discussions about who will get what, there is an important part of the early divorce process itself that needs to be dealt with.

unreasonable behaviour

Showing that a marriage has irretrievably broken down

If you want a divorce in England and Wales, you would have to show that your marriage has irretrievably broken down.

It was possible to do this by establishing one of five acts:


In order to cite adultery as grounds for divorce, you needed to establish that your spouse had sex with a member of the opposite sex. However, it’s important to point out that if you discovered this more than 6 months previously and continued to live with your spouse as a couple during this time, you won’t be able to use adultery as a reason for divorce.

Separation for more than 2 years (with consent)

If you and your spouse had lived apart from each other for more than 2 years and you both agree to the divorce taking place, you could use this as the reason that you are divorcing.

Separation for 5 years (without consent)

If you and your spouse had been separated and lived apart from each other for more than 5 years, you can cite this as a reason for your divorce. Unlike the reason above (separation for more than 2 years), your spouse does not have to agree for you to use this reason.


In order to use desertion as grounds for your divorce, you would have needed to show that your husband or wife has left you for more than 2 years in the past 2.5 years. It’s vital that they left you without your agreement, without a good reason and that they did it so that they could end your relationship.  Even if you have lived together with your spouse for up to 6 months in this time period, you could still use desertion as grounds for divorce.

Unreasonable behaviour was the most common ground for divorce in England and Wales. We will discuss why this is the case in more detail below.

In order to use unreasonable behaviour as grounds for divorce, you would need to show that your spouse has behaved so badly that you can’t reasonably be expected to live with them any longer.

What does unreasonable behaviour mean in a divorce?

If you were the petitioner (the person who filed the divorce petition) and cited unreasonable behaviour as your grounds for divorce, you would have needed to give at least one example of this behaviour. How many examples you were required to provide depends upon various factors so, as is still the case, it was always a good idea to seek advice from a specialist solicitor.

However, there is nothing to tell you what is and what is not deemed as unreasonable behaviour.

In law, unreasonable behaviour is defined as:

“When the respondent has behaved in such a way that the petitioner cannot reasonably be expected to live with the respondent.”

In essence, this means that the courts will look at whether you can reasonably be expected to still live with your spouse, despite their behaviour.

Unreasonable behaviour examples

What is and what is not unreasonable behaviour can be very subjective. One person may find the way that their spouse is behaving is completely unacceptable, whereas this type of behaviour may not bother another person at all.

For example, a wife may say that her husband is spending too much time training for triathlons and other sporting events and consequently is not spending enough time with her. Another person may see this as a benefit, as they have more time to take part in hobbies of their own.

Common examples of unreasonable behaviour included excessive drinking or gambling problems.

Other examples of unreasonable behaviour include:

  • Verbal abuse
  • Lack of sex
  • Lack of support
  • Domestic abuse

As the majority of divorces are undefended, unreasonable behaviour rarely got tested in the courts. However, one such (very unusual) case involved a woman who was refused a divorce from her husband. She is now reportedly going to argue that she should not have to prove unreasonable behaviour and is heading to the Supreme Court to do this.

unreasonable behaviour

Unreasonable behaviour was the most common grounds for divorce

In their statistical bulletin regarding Divorces in England and Wales: 2016, the Office for National Statistics reported that unreasonable behaviour remained the most common grounds for opposite-sex couples divorcing.

The ONS said that 36% of all husbands and 51% of all wives petitioned for divorce on these grounds.

In its report, the ONS stated that: “Unreasonable behaviour has consistently been the most common ground for wives petitioning for divorce since the late 1970s; previous to this, the ground was named “cruelty”.”

Interestingly, unreasonable behaviour has only been the most common ground for husbands petitioning, since 2006. Prior to this, in the 1980s and 1990s, adultery was the most common ground for this group, whereas between 1999 – 2005, it was separation for more than 2 years (with consent).

One of the possible reasons that unreasonable behaviour is the most common ground for divorce, is that out of the four other grounds, three of these require a wait of a number of years before they can be used as grounds for divorce.

The only other ground left that doesn’t require a lengthy wait to divorce, is adultery. However, adultery can be more difficult to prove than unreasonable behaviour.

Additionally, contrary to popular belief, adultery in the eyes of the law involves sexual intercourse with someone of the opposite sex. Other kinds of sexual contact, or a sexual relationship with someone of the same sex, could not be used to establish adultery in a divorce petition.

Moreover, adultery could not be given as a reason for divorce if you continued to live with your spouse as a couple for 6 months after you discovered what they had been doing.

Divorcing couples ‘lie to courts’?

Back in 2015, the Independent published an article regarding research by family justice campaign group Resolution, which revealed that over 27% of couples who cited unreasonable behaviour “admitted their claims were not true, but were the easiest way of getting a divorce”.

Resolution’s chair at the time, Jo Edwards, reportedly said: “As our research findings show, the current system is causing couples to make false allegations in court in order to have their divorce finalised within a reasonable time. This charade needs to be ended.

“The alternative, living for two years as a separated couple before divorce proceedings can be started, is financially and emotionally untenable for many people.”

‘No-fault’ divorce

Previously In England and Wales there was no such thing as a ‘no-fault’ divorce. In 2019 a new law was passed that allowed for a ‘no-fault’ divorce. The new law became active in April 2022.

Many people argued that the system of a fault divorce and blame is not only archaic, but it is also damaging, as it causes resentment between the couple at a time when they need to work together to come to an agreement about what will happen to their children and their assets when they go their separate ways.

Although no-one is arguing that all divorces could ever be completely amicable, it does seem logical to assume that now there is a ‘no-fault’ divorce where no blame was necessary, things should be, more often than not, a little less hostile.

Indeed, many believe that until there is a ‘no-fault’ divorce where there is no need to apportion blame, the old system was going to continue to stoke the flames of confrontation between divorcing couples.

Before the new law was passed a representative of the Office of National Statistics commented on the number of divorces in England and Wales, Resolution chair, Nigel Shepherd said:

“…there are tens of thousands of couples who are currently discouraged by the current system from taking a non-confrontational approach to divorce. For many separating couples, the need to apportion blame on the divorce petition can introduce unnecessary conflict, which adds to the stress and heartache for the couple themselves and, crucially, any children they may have.”

“For decades, ‘unreasonable behaviour’ has been the most common reason for divorce among opposite-sex couples, yet many are forced into playing this ‘blame game’ by our archaic divorce laws.”

“That’s why we have repeatedly called on the government to legislate for no-fault divorce, and will continue to do so. This call is echoed by senior legal figures, such as Baroness Hale, the President of the Supreme Court, and Sir Paul Coleridge, the Chair of the Marriage Foundation.”

“In the face of such overwhelming support, and with the Supreme Court due next Spring to hear the appeal of Mrs Owens, whose divorce has been denied because of the current law, the government needs to listen and take action.  It’s time to make no-fault the default.”

The No-fault divorce UK law reform will make the process of separation a lot more convenient for partners. According to this law, you do not have to blame your partner for filing a divorce. 

Either party can start the proceedings. Couples can also file the divorce with a joint application. This reform of the divorce law will make proceedings easier as you won’t have to blame your spouse. 

Is there a way to make our divorce more amicable?

Now the law has changed to a ‘no-fault’ system, it is a lot easier to make a divorce more amicable.

It may be wise to use a mediator, an independent third party, could help you with discussions if you wish. Alternatively, you could seek advice from solicitors experienced in collaborative law. Collaborative law is a process involving four-way meetings with you, your spouse and your respective solicitors, which take place with the aim of coming to an agreement about various elements of your divorce. 

Through these mediums, you could work with your spouse to come to agreement about the reasons you will cite for divorce.

Whilst in England and Wales it usually makes no difference who files for the divorce and who is the respondent, this may not be the case if your divorce goes through in another jurisdiction. This means that it’s vital to get legal advice as soon as possible if you think there could be an international element to your divorce.

Could you contest unreasonable behaviour?

Most divorces in England and Wales go through uncontested, without either spouse defending the divorce. This means that unreasonable behaviour is rarely tested in the courts.

If you don’t agree that unreasonable behaviour is the reason for your marriage breaking down, you are legally entitled to defend the divorce. Defending a divorce can be both costly and time-consuming and ultimately, the judge may decide that they will grant the divorce anyway.

If you did agree to the divorce but disagree with the unreasonable behaviour that your spouse has cited, you may want to state this in the “Acknowledgement of Service” document. Alternatively, you may want to submit a Cross Petition.

Sometimes, talking to your spouse and agreeing the grounds and examples that will be cited on the divorce petition before applying for a divorce, can help to avoid conflict further down the line. However, this will not be possible (or indeed advised) in all instances, particularly if there is an international element to the divorce. Always seek advice from a solicitor regarding your specific circumstances.

How long did an unreasonable behaviour divorce take?

Unreasonable Divorce timescales varied significantly. Usually, it took between 6 months to a year to get a divorce. It could have taken much longer than this, especially if a financial settlement could not be agreed. Usually, it is the financial negotiations which lengthen the divorce process, rather than the divorce itself.

An unreasonable behaviour divorce could take anything from 6 months to over a year. The precise period of time will depended upon a number of different factors, including the complexity of the finances of each spouse.

The majority of the time, it is the financial settlement which lengthens the divorce process, rather than the unreasonable behaviour divorce itself.

What were the other grounds for divorce?

As well as divorce for unreasonable behaviour, there were four other possible grounds for divorce:

  • Adultery – you needed to establish that your spouse has had sex with a member of the opposite sex, committing adultery with a member of the same sex was not considered in divorce proceedings
  • Separation for more than 2 years (with consent)
  • Separation for 5 years (without consent)
  • Desertion

Other than adultery, which was more difficult to prove than unreasonable behaviour, the other grounds required a wait of a number of years before they could be used as grounds for divorce.

How can our expert divorce solicitors help you with your divorce?

Our expert divorce solicitors can help you with a range of legal issues relating to child abduction, including:

Contact our expert divorce solicitors for divorce advice

For more information call our divorce solicitors on 0845 862 5001 or email

Our expert divorce solicitors offer a nationwide service. We have client meeting office facilities available, in order to have face-to-face client meetings/conferences as and when required in:

Please contact us for more details.

More helpful family law blogs

Was this article helpful?

20th June 2022

Chess Piece

Make the first move

Find out how we can help you, call us on
0333 311 0925 or email us today.

Contact Us
Back up to top Back to Top