So, part of it is, that if one attractive person finds you attractive, other people are more likely to find you attractive.
Humans are an odd bunch, like that.
The other side of it, is that a truly astonishing number of people go through life being told- and believing- that they need to have a “serious” relationship to be happy/successful/not a total waste, and then there’s the biological hardwiring that more or less confirms this is true.
Sometimes, to the point that they jump from one shitty relationship straight into the next.
As someone in an ENM relationship, no. If you're an awkward nerd who happened to hit it off with one person, you're still an awkward nerd when trying to hit it off with a second.
It is well known that, when you're single nobody wants you, but the second you manage to fool someone into relationship with you, you're the most wanted man around.
I'm just speculating here based on my own experience, but I wonder if part of it is also something subtle in your attitude that others pick up on.
When I met the man who is now my husband, I wasn't even looking for a relationship. I was just enjoying my life, exploring new hobbies, and was in a good place mentally -- that is, I was fine if I ended up single for the rest of my life.
I imagine married people also tend to be in a similar frame of mind where they aren't looking for a relationship, and maybe there's a confidence that comes out of that that is attractive to others.
If you're a man, put on a wedding ring and go out to the bar and see for yourself. This may work if you're a woman too but I can not claim to have done the research on that one.
I have my dad's old wedding ring, I may try this. But the issue becomes I don't want to have a serious relationship with a woman who only likes me because she can "destroy my family" essentially (whether the "family" is fake or not.) Something seems seriously wrong with those people.