Agree entirely that it should all be for mutual enjoyment. But enjoyment can mean different things for different people. For my wife it's mainly the pleasure of getting to suck off and be fucked by a variety of men on a regular basis and also to have the thrill of discovering a new male body. She has a high sex drive, is much younger than me and 'needs' it. I love her so I want that for her. But also for me, I admit, there is a certain thrill in seeing her taken, having her taken from me for a while, out of my control, on loan as it were. To see her respond sexually, even romantically to a degree, to another mans advances, his touch, his caresses, his words, his kiss..... his forceful thrusts.... it's a real turn on. I love to see her spread her legs and be available to another male. I love to see her submit and enjoy it. Not for everybody, I am quite aware, but for me it's a big thrill and turn on.