Signs They’re Having an Affair

Medically Reviewed by Sabrina Felson, MD on December 04, 2022
4 min read

An affair is the act of infidelity within a relationship. “Infidelity” cannot be precisely defined because different relationships establish different boundaries with different definitions of fidelity. Relationships are contracts, implicit or explicit, and an affair breaks that contract, whatever it may be.

There are many reasons that affairs, or adultery, happen. Common reasons include:

  • Unaddressed problems in the marriage 
  • Breakdown of communication and emotional support
  • Mental health issues or addiction
  • Loss of affection or caring
  • Physical health issues, particularly ones that create sexual obstacles

While it used to be more common for men to engage in affairs, men and women now engage in infidelity at about equal rates. In one study 2-4% of spouses admitted to having an affair within the past year.

None of the symptoms of affairs discussed here should be taken as definitive or absolute. If you suspect your partner of having an affair, your first step is to talk to them. However, there are certain warning signs of which you can take note.

There are two main types of affair: sexual and emotional. Both can hurt the partner who is betrayed. Sexual affairs may cause more initial anger, but emotional affairs can hurt feelings just as strongly. 

Sexual Infidelity

In sexual infidelity, the unfaithful partner engages in some kind of unlicensed sexual activity with someone outside the marriage or relationship.

Emotional Infidelity

Emotional infidelity can be harder to define, particularly in the age of the internet.

It happens when someone goes outside of the relationship in order to meet certain emotional needs that their partner feels should be met within their relationship. They may confide in them about troubles, either with their partner or unrelated problems. The emotional intimacy can independently threaten a marriage or can lead to a sexual affair.

Short of catching the other person, there is no sure sign of an affair. However, many people having an affair display one or more of the following behaviors:

Change in Treatment of Partner

People having an affair often change the way that they treat their partner out of guilt or frustration. The change can go in several different directions. 

  • They can demonstrate apathy towards their partner’s sexual interest and needs. 
  • They can overcompensate with displays of affection and sexual aggression.
  • They can become increasingly argumentative and quick to anger. 

Anxiety and Avoidance

An unfaithful partner may be particularly apologetic or unable to look the other person in the eye. They also may be reluctant to spend time together. 

Secrecy is also a bad sign. If your partner gives the impression of hiding something from you or being unwilling to talk about something, confront them.

Active or Passive Expression of Dissatisfaction

They may complain of sexual boredom or simply act bored with partner sex, giving the impression of someone just going through the motions. 

They may raise the possibility of ending the relationship or seeing other people. Or they may simply withdraw from the relationship, failing to observe important occasions or to express their love.

Changes in Normal Routine

Any of these might indicate an affair: 

  • Change in physical appearance
  • Unexplained changes in schedule or habits
  • Excessive sleep 
  • Change in diet
  • The introduction of new and unfamiliar sexual positions 

Physical or Economic Signs of an Affair

The cliches exist for a reason. If you find lipstick on their collar or bite marks on their thighs, don’t be afraid to ask about them. Equally, if money is suddenly disappearing or credit card bills have strange charges, they may be engaging in expensive and clandestine activities.

Most dangerously, they could catch an infection and spread it to you. If you suddenly discover yourself with a sexually transmitted disease and have only slept with your partner, they may have cheated on you.

Odd Behavior When It Comes to a Third Party

They may act strangely when a certain name comes up, or people may tell you that they’ve seen the two spending a lot of time together.

Internet behavior can also change. They may spend a disproportionate amount of time or energy engaging with one other person. 

Your relationship is between you and anyone else involved. There is no one right answer. You may need to leave or you may need to give the relationship another chance. 

Whatever your decision, seek out the support you need, whether that’s from a friend, a therapist, or a spiritual leader.

Perhaps the best thing you can do is to take some time. Give yourself a little bit of room to process and overcome the initial shock. If you do decide to stay in the relationship, the following may help:

  • Be accountable for your actions and be firm in your demand that they take responsibility for theirs.
  • Consult a marriage counselor.
  • Make a plan together. If trust is broken, how could it be restored? What does the timeline for that look like? Move forward together as a unit.