@freemo Well, I would think that the expectation would be that if one isn’t in a boyfriend-girlfriend relationship, they’re free to date however many different people they want, and I think the distinction between monogamy and non-monogamy is important enough to warrant its own label.
Like you can just say “we are monogamous” and that conveys all the info needed.
At the same time, one can also say “we are boyfriend and girlfriend” without saying anything about monogamy.