There is nothing right or wrong about how we choose to relate sexually with people. There are just our desires and whether we honor them or deny them.
When we do not honor our desire to be loved, adored and supported as the apple of our beloved's eye, we settle for something else. Then when we notice that our beloved needs to entertain sexual thoughts and fantasies about other people, the ego will act as if it shouldn't bother us and judge that we should try to "be open minded" about it.
But being open minded doesn't mean denying our truest desires. When we claim our worthiness to have our desires fulfilled - we can let go of whatever is moving toward a different goal.