Me and a girl I know are friends with benefits. I don't see whats wrong, we fuck on a regular basis and friends know.
My friend with benefits started as a boyfriend. We dated for a while, split up and saw other people for a while but realized we missed sex with each other. So for 7 years we dated who we wanted and had sex in between those relationships, and for the most part, during. I trusted him with my life, we laughed, we hung out, typical friend stuff, but we both ended up finding people we wanted to settle down with and both got married about a year later, a month apart. It was fun while it lasted, that's it.