The term "love rat" is commonly used to describe someone who is unfaithful in a romantic relationship. However, there are many synonyms that can be used to convey the same meaning. Some more polite alternatives might include "cheater," "infidel," or "adulterer," while more vulgar terms could include "player," "cad," or "skank." Other phrases that can be used to describe someone who is unfaithful include "two-timer," "backstabber," or "traitor." Regardless of the word used, the message is clear - being unfaithful in a relationship is unacceptable and can have devastating consequences for those involved.