As a Bull what I have heard from numerous women is that alot of these men wanted to join the lifestyle but wasn't really ready to see their wives let their hair down and get down and dirty with with other men. I had a woman tell me that her husband took her to a swing party and she got some BBC and went buck wild and basically fucked every BBC at the party and her husbands face said that he was not happy with her. She told me "I don't that that will ever happen again"!
This is why couples entering the lifestyle need to come to the full agreement that they are going to fully jump into the lifestyle and have as much fun as possible an not judge each other or we are going to go and just be observers and voyeurs of other people having fun but what you don't do is let each other off the leash then get mad at the fun you have.
As a Bull who primarily has sex one on one or in threesomes with hotwives when a husband, a wife, a couple, a boyfriend, or a girlfriend contacts me about meeting them and having some lifestyle fun I have one main rule: I require the woman to be uninhibited and free to express herself sexually how ever she chooses!
For example: if we have a threesome and you know your wife doesn't like anal sex and you guys don't do it at home, but as the Bull I fuck her so good all of a sudden she says "I want to try this big black cock up my ass"! There should be no objections because that's what she wants to. Fortunately for me when the unexpected gifts happened during my experiences it always went well but I have heard from other Bulls that hubby got jealous and didn't let things happen or complained or shut the whole thing down.
This is why I tell them up front when we are talking about expectations and boundaries that "she must be freely uninhibited to express herself sexually" or I am not interested.
From a bulls perspective be all in if you get into it or stay out because all you will do is upset yourself!