cheater

2 definitions • 4 examples

a person who behaves in a dishonest way in order to win or get an advantage:

The Inland Revenue has many ways to catch cheaters.

Athletes who break the rules to win are cheaters.

a person who has a secret sexual relationship with someone who is not their husband, wife, or usual sexual partner:

Emma found out her boyfriend was a cheater.

I can understand someone staying with a cheater if they have small children to care for.