Infidelity Versus Adultery: What's The Difference?

If you're in a monogamous relationship, the idea of finding out that your partner has been cheating might be enough to keep you awake at night. According to Family Process, infidelity occurs in one out of four marriages. However, depending on the way infidelity is defined within a marriage, that number can easily shoot up to as high as 50% (via research published in The Journal of Sex Research). Speaking of definitions, the terms infidelity and adultery are commonly used interchangeably. However, they do not actually share a definition.


The difference between adultery and infidelity can change depending on the context of the specific discussion, but adultery is always more inflexibly defined than infidelity. Adultery is also sometimes used as a legal or religious term and may take on a separate meaning within those realms (via Cornell Law School). As far as the typical layperson's use of the words, here is a simple guide to the difference between adultery and infidelity.

What is adultery?

When it comes to the difference between adultery and infidelity, adultery is the easier term to define. Adultery, as defined by Merriam-Webster, specifically refers to physical sexual acts that occur outside of a marriage or other committed romantic relationship. Before the invasion of online communication, adultery was a more common form of cheating within a monogamous relationship (via the American Psychological Association). If your partner has a few too many drinks at a bar and hooks up with a stranger, they have committed adultery.  


Whether a physical affair is more serious or more damaging to a relationship than an emotional one is a controversial topic. The truth may be that the answer varies from couple to couple — or even from individual to individual — and can be greatly impacted by the potential outcomes tied to extramarital sex, including unintended pregnancy and sexually transmitted infections. According to Brides, both types of affairs lead to about the same risk of the relationship ending. 

What is infidelity?

If adultery only refers to physical sexual contact outside of a committed relationship, infidelity is left to encompass all other forms of cheating. Merriam-Webster defines it as a romantic or sexual relationship with someone other than your spouse or partner. However, which types of interactions qualify as romantic or sexual in nature can vary drastically from one partner to another. This an excellent reason to have a discussion at the beginning of your relationship during which you and your partner both define what type of behavior you would consider cheating and create specific ground rules. Be sure to cover common gray areas, like flirting, pornography, and sharing deep emotional connections (via Banner Health).


If infidelity — or adultery — takes place in your relationship, it doesn't always have to be the end. According to Couples Therapy Inc, most marriages actually survive affairs, as long as both parties are committed to healing the relationship. First, make sure you're valuing yourself and only staying in the relationship because it's what you truly desire and not because of pressure from your partner or society. If it doesn't feel right to stay, there is also no shame in moving on.