Monogamy is a ugly word, it sounds like something to be endured rather than something to be enjoyed. Faithful is a nicer word. I am faithful to my sweetheart in that I could never lie to him, I am never going to love anyone else, I will do anything for him including sacrificing my life, but to say I will never have sex with anyone else is a promise not worth making. If I made that promise it only risks causing grief when it inevitably gets broken by one of us. Of course you don't play away very often and never bareback with strangers but a little bit of harmless fun is no more than that. We have more important things to worry about than a bit of harmless fun.