You don't have to be into kinky things to have this feeling. I've been bisexual my whole life. I've had relations with both men and women, eventually getting married and having kids. I told my wife early in our relationship about me and my past, and my desired future.
I know that she like regular sex, and I avoid pursuing homosexual/bisexual acts with her since it isn't her thing. I personally don't cheat, but I do masturbate to gay porn and have an@l play with myself. However, from time to time I want to explore with my wife. I ask about MMF 3somes, or even just her using a strap-on.
In the end, I never get all of me satisfied, and I get guilted for even asking the questions.
I ask myself all the time, why I should feel guilt over who I am, or having desires or needs?