What Constitutes As Adultery in the UK and How Has the Law Changed?

Aug 2026 In: Family

Changes to Legislation

Following the Divorce, Dissolution and Separation Act 2020, which came into force on April 6, 2022, England and Wales moved to a “no-fault” divorce system. This means adultery is no longer a legal ground or reason required for divorce. You no longer need to assign blame or prove misconduct to end a marriage.

Does Adultery Still Exist in UK Legal Terms?

While the legal definition of adultery still exists in common law, it no longer plays a formal role in getting a divorce.

Historically, adultery was legally defined as:

- A married woman has had sexual intercourse with a man other than her husband

- A married man has had sexual intercourse with a woman other than his wife

Can I Use Adultery as Grounds for Divorce?

Under current law in England and Wales, you do not need to prove adultery or unreasonable behaviour to get a divorce. The only requirement is a statement that the marriage has irretrievably broken down.

The Divorce, Dissolution and Separation Act 2020 is the official legislation that reformed divorce law to include “no-fault divorce”.

What Does This Change Mean?

Old Law	New Law
Applicants for divorce had to prove one of 5 “facts” to show their marriage had broken down, such as adultery or unreasonable behaviour.	You do not need to provide reasons or evidence of misconduct, when applying for divorce. The court accepts a simple statement confirming that the marriage has broken down.
One spouse had to formally petition against the other.	Couples can now apply jointly if they agree on ending the marriage amicably. They can still apply separately, if preferred.
A spouse could formally dispute a divorce application, forcing long, costly court battles.	A spouse can no longer defend or block a divorce. A court will proceed as long as one party states the marriage has broken down.
A divorce could technically move forward immediately upon filing.	The Act created a mandatory 20-week cooling between submitting the initial application and applying for a conditional order. This allows couples time to organise finances and child arrangements.

How Infidelity Affects Finances and Child Arrangements

When a marriage breaks down because of an affair, it is completely natural to feel that the unfaithful partner should face consequences. However, under family law, the legal system separates emotional responsibility from financial and practical arrangements, and an affair does not legally affect your divorce.

Does adultery affect the financial settlement?

Almost never. In the eyes of the family courts, infidelity is a reason for a relationship breakdown, not a legal offence that triggers financial penalties.

How Assets Are Divided

Financial settlements are governed by Section 25 of the Matrimonial Causes Act 1973. The court’s primary goal is to reach a settlement that is fair and meets the future housing and living needs of both parties, especially where children are involved. This includes:

The income, earning capacity, property and other financial resources which each of the parties to the marriage has or is likely to have in the foreseeable future;
The financial needs, obligations and responsibilities which each of the parties to the marriage has or is likely to have in the foreseeable future;
The standard of living enjoyed by the family before the breakdown of the marriage;

The Exception: Section 25(2)(g) “Conduct”

Section 25 of the Act does mention a party’s “conduct,” but under section 25(2)(g), the court will only take conduct into account if it is so extreme that it would be “inequitable [unfair] to disregard it.”

Personal affairs do not meet this threshold: Hurt feelings, dishonesty, or infidelity are excluded by judges when dividing marital assets.
Financial dissipation: Conduct may become relevant if your spouse recklessly spent significant joint marital funds on their affair—such as buying expensive gifts, funding lavish holidays, or paying rent for a partner. Courts do not penalise the infidelity itself. Instead, they penalise reckless overspending that unfairly reduces the pool of money available for the other spouse.

Does an Affair Affect Child Arrangements?

No. An extra-marital affair does not impact a parent’s legal rights, custody arrangements, or contact time with their children. Under the Children Act 1989, the child’s welfare is paramount.

Parenting vs relationship behaviour: Family courts have strict distinctions between a person’s behaviour in a relationship and their capabilities as a parent. In the eyes of the court, you are not unfit as a parent if you have an affair.
Parental rights remain the same: Parental responsibility is not diminished by infidelity, the person still has the right to be involved in decisions about their child.
Contact is only restricted if the child is at risk of harm. The court will only limit a parent’s contact if there is a direct risk of physical or emotional harm to the child, not because of an affair.

What Can I Do Next?

Although the court will not penalise your spouse for an affair, there are practical steps you can take to protect your future and ensure a smooth, fair resolution:

Apply for a Financial Consent Order: If you and your ex-partner agree on how to divide money and property, you need to apply for a consent order to make it legally binding. This stops your ex-spouse from making financial claims against your future income or assets.
Establish a Workable Co-Parenting Arrangement: If you have children, focus on establishing a clear parenting plan early on. Mediation or collaborative law can help both parties agree on contact schedules outside of court

How Can Our Legal Team Help You?

If you are navigating separation after an affair, you don’t have to do it alone. Our specialist divorce solicitors have a great deal of experience and will be able to assist you every step of the way.

Read more on our Divorce Solicitors page.

Get in touch today for expert help and advice.