I suspect my partner is cheating, but they deny it. What should I do?
If your partner is cheating, he/she is not likely to admit it. The more you accuse, the more they will deny.
I believe you have a right to know what is going on. I would encourage you to note all the evidence that leads you to conclude he/she is involved in an affair. (See the "Signs of an Affair" list below.) It's unlikely that a single indicator will prove something is going on, but any pattern of changed behavior, along with your gut suspicions, is important to consider. You should gather as much information as possible before discussing it with your partner.
Ideally, you should remain in control of yourself when you question your partner. If you are likely to lose your temper, you may want to consider writing a letter and asking your spouse to read it alone or with you nearby. If there is any chance that they might come clean (a possibility if the affair has run its course or if they are struggling with a weight of guilt), you are more likely to achieve the desired result with controlled confrontation rather than with angry accusations. Anger puts people into a "fight or flight" mode that prohibits healthy dialogue. Don't assume; don't blame; just ask. But don't give them all the evidence you have. Be sure to hold out some important information because this will be a good indicator of how honest they are willing to be. If they try to create a story to explain away your evidence, your withheld information will likely make their continued deception obvious.
In most cases, they will deny an affair and will likely try to make you feel ridiculous for even suspecting such a thing. Listen; don't argue. Ensure you have clearly communicated your questions and concerns and let them respond. Do the answers make sense? Is there a chance you got things wrong?
You have the right to know the truth if you still have doubts. You may want to wait and try again to present your spouse with troubling observations, but at some point, you may need to take more deliberate steps to discover the truth. See the entry Trying to Catch Your Spouse in an Affair for more information.
What are some of the major signs of an affair?
Note: You won't see all of these, but any of them should cause you to question, and multiple signs cause more concern.
Relationship Changes
increased emotional distance from you and other family members
increased criticism of spouse/partner
a change in their sexual behavior with you (less sex or suddenly trying new things)
Financial Changes
unexplained expenses/charges that your partner claims are work or expense account related
unexplained ATM withdrawals
sudden secrecy regarding online banking accounts
higher mobile phone bills
Behavior Changes
unusual changes in personal or work schedules
the sense that their thoughts are often "somewhere else"
sudden interest in new activities or hobbies
unusual interest in specific songs or music
heightened attention to appearance (buying new clothes, getting in shape)
being freshly showered at odd times of the day/night
taking off wedding band at certain times/places
Increased Secrecy
unaccounted for time away from you
being vague about where they were or who they were with... speaking in generalities, and avoiding specifics
overly protective with phones and other communication devices
secrecy with phone calls, emails, or text messages
being overly defensive about the person you suspect
Other Evidence
the smell of someone else's perfume or cologne
an unexplained sexually transmitted disease
possession of an additional cell phone
numerous calls or text records to the same number