newbie26 saidWhat should I do?? What would you do??
Ignore it, leave it alone, say nothing. You mention your gaydar, but I'll go out on a limb here and give you another gay stereotype I find a trademark of many gay men: they meddle in things that don't concern them, especially other people's personal business about which they weren't invited to comment. And based on rather dubious evidence in this case.
She being your best friend is not justification for you to stir up trouble. And beware of your own motivations, if deep down inside you're not a bit resentful & jealous that she's spending time with him that you'd rather have go to you. Your thread title of "My girl is dating..." is very revealing. In fact, at first I wondered if you meant your daughter, not knowing your age, or if you're a Lesbian coming here for advice.
And what happens if "your girl" does move on to another guy? Are you going to screen him for her, too, and find some different flaw in him to tell her all about?