Adultery as Grounds for Divorce

In the UK, adultery is one of the five facts which may be relied upon by the petitioner for divorce. It must have taken place during the marriage and not before, so if you committed adultery before you married your spouse it cannot be used as a ground, even if they knew about it at the time.

If your spouse committed adultery and you want to divorce them, you will need strong evidence that they did indeed do what is alleged, otherwise the Court might refuse to grant a divorce petition. The only exception is with proof of desertion , where there is no need to show any proof of adultery, but this will depend on the circumstances.

Unreasonable behaviour and adultery are two of the most common issues cited in a divorce petition. If you wish to file a divorce on the grounds of adultery, you must be able to prove that the marriage broke down due to infidelity and not another issue.

Adultery and Legal Definitions

Before claiming that your spouse has committed adultery, it is important that you recognise what is meant by the term as it may not be what you think. The term generally refers to sexual intercourse between a married person and somebody who is not their spouse, while the other party may or may not be married.

If you file for divorce on these grounds, it is possible that the court will require you to prove that this act occurred (and if so, what its extent was), which wouldn’t be necessary with other types of grounds.

To prove adultery, you will need to gather evidence that your spouse was unfaithful. This could be through photographic evidence or statements from the person who committed the act with your partner. You can then use this proof to file for divorce on the grounds of adultery.

There are several conditions that you must fulfil if you are to divorce on the grounds of adultery:

The application for divorce must be filed within six months of you first discovering that your spouse committed adultery.

You must cite the adultery committed by your partner. You cannot cite adultery as grounds for divorce if you committed it yourself.

Your spouse must have had sex with someone of the opposite sex.

Note, that the law on adultery is very specific, so finding out that your partner is using a dating app, meeting or messaging another person is not classed as adultery even if you believe that it is.

There are also other rules that you must comply with to successfully divorce on the grounds of adultery. One of which is that you must not have lived with your spouse for more than six months after finding out about their infidelity. If you continue to live with them beyond six months, you will have to file for divorce based on other grounds.

Proving Adultery – Challenges

It may be particularly difficult to prove adultery if your spouse fails to admit their infidelity. That said, if your spouse does admit it, what’s known as an ‘Acknowledgement of Service’ can be completed from the divorce petition. In this instance, a judge can accept the reason and the divorce can proceed.

Challenges can arise when your spouse fails to admit their infidelity. Often, it is impossible to prove this so you would need to divorce on other grounds. When this is the case, the most common course of action is to cite unreasonable behaviour as the reason for divorce. In doing so, you can provide additional information, typically between four and five paragraphs which you submit to the court to detail the unreasonable behaviour of your spouse. It is also an opportunity for you to explain why it is no longer possible to be married to them.


Divorce petitions must be filed within six months of finding out about the adultery. Where you continue to live with your spouse beyond the six months, the courts will understand that this means you accept the adultery and you will therefore need to cite another reason if you wish to file for a divorce.

When it comes to financial settlements, it is very unusual for the court to take behaviour into consideration, unless it is directly related to finances.

One of the main factors that affects a financial settlement is the duration of the marriage or civil partnership as well as the number of dependent children, the impact of earning potential both currently and in the future.

Adultery can be a difficult area of law to navigate, both in terms of emotions and at times hostility where there has been a complete breakdown in the marriage. This is why it is essential to seek expert legal advice to understand your rights and what options are available to you

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