What Legally Constitutes Infidelity in a Marriage?

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Rachael Pace, Author

Rachael Pace

Expertise: Mental health, Parenting

Rachael Pace inspires with motivational articles on loving partnerships. She encourages making room for love and facing challenges together.

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Updated: 18 Nov, 2022

Table of Contents

Cheating hurts deeply: Infidelity can shake trust, but couples can heal by prioritizing honest conversation and emotional closeness.
Emotional infidelity matters too: Rebuild closeness by sharing vulnerabilities and creating safe spaces to feel seen.
Focus on growth, not fault: Prioritize connection over blame and seek support to strengthen your bond.

Cheating is a hurtful event that can unravel a marriage. Infidelity and marriage cannot coexist and the repercussions of dalliances in a marriage often lead to an irreparable damage to the bond to love.

The line that defines cheating is crystal clear in your mind, but what you see as infidelity in marriage or an affair may not be recognized by the legal system.

So what constitutes an affair?

An affair is a sexual, romantic, passionate or a strong attachment between two people, without either of the individual’s partners knowing.

Is it worth it to file for divorce on the grounds of adultery? Knowing the different types of infidelity, as well as how the law sees them is important, especially if you are legally separating from your partner or are considering getting a divorce.

When filling out divorce paperwork, you will have to state whether you are filing for a “fault” or “no-fault” divorce. This section will ask you to identify whether you are separating because you no longer want to be married, or because of adultery, incarceration, desertion, or abuse.

Here is everything you need to know about state-defined cheating and what the law says about your unfaithful partner and what cheating in a marriage is called in legal terms.

Different forms of infidelity in marriage

What is cheating in a marriage?

As a married man or woman, you would agree that penetrative intercourse is cheating. You likely would also agree that you would not be comfortable with your partner giving or receiving oral or anal sex from someone else. This is also cheating.

Emotional infidelity in marriage is another avenue that most married couples consider a form of cheating. This occurs when there is no physical affair present, but an emotional relationship with someone outside of the marriage has persisted and it has been kept a secret.

With all these different facets of infidelity in marriage, you might be wondering what aspect of cheating the courts legally accept as a form of infidelity.

What the courts believe

What is considered cheating in a marriage? If you are looking at the legal definition of infidelity, law has different definitions of what constitutes cheating in a marriage.

You will be happy to know that the legal system across the United States considers both physical and emotional affairs to be valid, including the use of social media or cyberspace to facilitate an affair.

Does it matter what legally constitutes infidelity in a marriage? What is considered infidelity? The legal term for cheating on a spouse is often referred to as adultery.

It is a voluntary relationship established between an individual who is married and someone who is not the individual’s married partner without the partner knowing.

While the courts will consider all aspects and facets of the reason for the dissolution of marriage, it won’t necessarily have an impact on how they choose to divide assets, child support, or visitations.

Jail time and legal consequences of cheating

Believe it or not, you can get your cheating partner in trouble with the law for being unfaithful or committing marriage infidelity. Indeed, there are many states that still have “adultery laws” which claim that anyone who is caught having sexual intercourse with someone other than their marital spouse can be punished by law.

In Arizona, cheating on your spouse is considered to be a Class 3 misdemeanor and can get both your cheating partner and their lover 30 days in jail. Similarly, Kansas finds both vaginal and anal intercourse with someone other than your husband or wife to be punishable by jail time and a $500 fine.

If you live in Illinois and really want to punish your partner, you can get your cheating-ex and his lover thrown in jail for up to one year (up to three years in jail with a $500 fine if you live in Massachusetts!)

Finally, if you live in Wisconsin and are caught cheating you may face three years behind bars and may be fined $10,000.

If these fines aren’t proof enough that the legal system has something to say about cheating.

Proving adultery

Reporter Photographing A Famous Vip Couple On A Romantic Date

Learning what legally constitutes infidelity in a marriage is important when talking to your lawyer and taking the matter to court.

The courts require you to have some form of proof that adultery occurred:

If you have hotel receipts, credit card statements, or evidence from a private investigator.
If your spouse is willing to admit it
If you have photos, screenshots from phones, text messages, or social media interactions that prove infidelity took place

If you don’t have such evidence, it can be difficult to prove your case.

Choosing to pursue a fault divorce

It is wise to think long and hard about whether or not you want to pursue a “fault divorce” with your ex.

Proving that an affair occurred in court will require additional time and money. You may need to hire a private investigator and spend additional time and expenses on lawyers’ fees to prove infidelity in marriage. It is a costly endeavor that may not work in your favor.

Talking about infidelity in the marriage is also personal and embarrassing to discuss in open court. Your ex’s lawyer may also attack your character and past behavior, pulling your personal and marital problems out in the open.

To some, proving an affair happened or airing their dirty laundry in the courthouse makes pursuing a fault divorce not worth the effort, finances, and pain. However, your particular state or circumstances may cause the courts to take adultery into consideration when deciding on property division or alimony payments.

Your behavior matters

Cheating couples, beware! If you are taking your spouse to court for an “at-fault divorce”, you need to consider your own behavior during your relationship as well. For example, if a wife finds out her husband has been unfaithful and cheats in retaliation, this can nullify her legal complaint of infidelity.

If both spouses have cheated in the marriage, a claim of recrimination or connivance will be called into question.

Talk to your lawyer

Before pursuing your legal separation or divorce, you should speak with your attorney about what legally constitutes infidelity in a marriage in your state, province, or country.

Some questions to keep in mind when talking to your lawyer is: Will proof of adultery affect the outcome of my divorce in such cases as alimony, a division of assets, or child custody?

What is going to be the best proof of infidelity to win my case?

Is it possible to change my mind about the grounds for divorce after filing?

Will it hurt my case if I have also been unfaithful after my spouse’s affair or earlier in our marriage?

It is wisest to consult a lawyer about adultery in your marriage before actually filing for divorce or separation. This way you will be able to take positive steps for proving your case before you are out of your marital home.

You need to know what legally constitutes infidelity in a marriage if you are planning on filing for a “fault-divorce”. Remember that while it may feel cathartic to have the courts side with you about your partner’s infidelity in marriage, fault-divorces are often costlier and emotionally charged than a regular divorce.

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Rachael Pace Author

Rachael Pace is a noted relationship writer associated with Marriage.com. She provides inspiration, support, and empowerment in the form of motivational articles and essays. Rachael enjoys studying the evolution of loving partnerships... Read more and is passionate about writing on them. She believes that everyone should make room for love in their lives and encourages couples to work on overcoming their challenges together. Read less