You don’t have to figure it out. They tell you the first chance they get if they are married.
It’s very insulting. Like they think the only reason you’re even talking to them is marital, or at least sexual.
If they’re not married, they bring up their girlfriend when you’re not talking about anything even remotely related.
It just shows they’re the one thinking about it. So I guess we should be flattered. But it is annoying because they already killed the friendship with their supposition.
The impulsive ones usually choose the one whose neuroses are complementary to theirs. Then they waste their whole life wondering why they picked that one. When they find out a partner is more complex than the early attractive forces it can be the end of that relationship. Seen it happen all to often.