It's dishonest to cheat on your significant other
Dave who is married to Ann is at a club with some friends when he's approached by a gorgeous woman who asks him to come home with her.
Dave wants to answer the woman's proposal.
Dave tells the woman  that while she's beautiful he cannot go home with her since he's promised to someone else.
Dave tells the woman that she is amazingly beautiful and that he would love to come home with her.
Ann finds out from the friends that Dave said no, and she is ecstatic that she has such a loyal and loving partner.
Ann finds out from the friends that Dave violated their relationship and is really angry with him and feels used.