There can be no duress involved and the agreement must be fair, with both parties obtaining legal advice and fully disclosing their assets. If you try to force your partner to enter into a pre-nuptial agreement then it will most lightly be seen as unenforceable.
A pre-nuptial agreement is particularly useful if, for example, you are a high net worth individual or someone entering a second marriage later in life who would like to keep your money separate from the shared property and wealth in your marriage. If, in the unfortunate situation of the relationship breaking down, you don’t have a pre-nuptial agreement, you risk all of your wealth being split 50-50 between yourself and your spouse.
If you and your partner cannot reach an agreement about what the pre-nuptial agreement will contain and you both still want to marry, then if your marriage ends in divorce, the court will decide how to split your assets. If this is unacceptable to you then you will have to consider whether it is right for you to marry. You cannot force your partner to sign an agreement.
It is important to note that child maintenance must always be paid whether or not you marry. You cannot opt out of child maintenance in a pre-nuptial agreement.