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What is your obligation to a "friend with benefits?"

Question of the night:

What is your obligation to your FB (fuck buddy) or FWB (friend
with benefits)?

Is there an obligation to hook up with them whenever they
want it?

If you get into a relationship with someone else are you
still obligated to give it up to the FB or FWB on the side?

Are these types of relationships earmarked with a vow of
silence? Is it OK to break that vow if you get pissed off?

I understand that most responses are subjective- but we
should have some ground rules we could all agree on, right?