> I think the distinction between monogamy and non-monogamy is important enough to warrant its own label.
Sure but you are claiming they are equivelant, at least for you. So now monogomy has two labels that mean the same thing.
> At the same time, one can also say “we are boyfriend and girlfriend” without saying anything about monogamy.
But no you cant because "girlfriend" only means monogamy to you, and **some** christian. It isnt universal. So unless someone specifically knows that girlfriend means monogamy to you, then you cant say that and convey the information. You would have to say "She is my girlfriend, and I believe girlfriend is the same as monogamy"
Even if we accept that 100% of christians think like you, which they dont, you'd still have to say "I have a girlfriend and I am christian" where otherwise you could just say "I am monogamous"