You shouldn't betray your significant other.
John is at a party with his wife Nancy when another woman comes up to John and propositions him for sex.
John wants to respond to the woman.
John tells the woman that he is happily married and that he has everything he needs in every way.
John tells the woman that since she is very attractive that he will definitely sleep with her right away.
Nancy is delighted that her husband is more attracted to her than anyone and only wants her and no one else.
Nancy is devastated that John doesn't care about her or their relationship and is willing to betray his vows.