To show that this irretrievable breakdown has occurred (and for you to be granted the dissolution of your civil partnership) you have to prove that one of four things has happened – either unreasonable behaviour, separation for more than two years (with consent), separation for five years (without consent) or desertion.
You will need to present the court with evidence that one of these four things has happened in order to prove that an irretrievable breakdown of the civil partnership has occurred. Without evidence in one of these categories the court will not be able to dissolve your civil partnership.
The only difference between this and the criteria for divorce is that you cannot use adultery as a reason for your dissolution, although you can include adultery as evidence of unreasonable behaviour.
If you are considering dissolving your civil partnership but are unsure as to which of the four categories you would use then you should seek independent legal advice on the matter.