You are making a lot of assumptions that seem to make sense to you but in reality are completely arbitrary.

Say, for me, I would not mind what OP's fiancee is doing, nor does she seem to mind it - I do not know why you decided that it is bothering the OP - she described what the guy is doing with a normal curiosity of a scientist; she does not appear bothered.

But I would never EVER accept cruelty and sexism in bed the way you do. It is just completely beyond me.

See how it is arbitrary? You have some sort of tastes and preferences that seem to make sense to you, but they might not make sense to others.