I fucking hate this term and the "idea" behind it. Why can't you just be friends who fuck. By this I mean "date" not with any great intention to plot a future, but just have fun. I mean, don't we usually think of the person we get intimate with as a friend, the person we love as a friend, the boyfriend is a friend, the husband too.
The reason I hate this term and all it seems to stand for: its a useless label that seems to set boundaries and lock you into a sort of deal, with the best of intentions someone always breaks the rules, it diminishes any real value to human relationships, it allows men to think differently about you, often putting you at risk of STDs because it allows for multiple little assignations, feelings often don't conform to rigid rules and imposed institutions.
So, neither of you are ready for a relationship, sorry to break it to you but you are already in a sort of relationship...one where all the other lovely nice things that happen in relationships will be off bounds and outside of the boundary.
You can set ground rules: no hugging, holding hands, supporting each other, no texts apart from arranging sex, no laughing, giggling, no nights out, no sharing meals, no flowers, no kisses, no gentle back rubs, fluffing hair, teasing each other, no flirting, no eye gazing, in fact everything that might create intimacy or stir up feelings must be off bounds lest one of you strays outside the golden rule; do not fall for each other. Does that sound fun?
FwB was clearly designed for men who want sex without the hassle of being decent human beings able to hold a conversation, a door open, or go halves on a meal out.