Having your suspicions that your partner is not being faithful to you isn't nice at all. Your heart may sink, and you may break out into cold sweats, but the fear of confrontation may be too high, just in case you've got it wrong. You'd need some sound evidence before approaching them with your accusations, but it can be hard to know what to look out for.
People who certainly do know what to look out for are private investigators - those hired to catch unfaithful partners in the act. They're clued in regarding suspicious things to look out for, and common signs that could suggest infidelity.
