[freyr]

Perhaps to you. To others, monogamy in a romantic relationship is a requirement and a reasonable expectation.

Couples should figure out where they stand on that, before they resort to kicking.

[king_jester]

It may well be that someone has a reasonable expectation of monogamy, but that's entirely irrelevant. If you don't like the way your partner acts in a relationship, you don't hit them, you talk about it and possibly break it off.