Well, I think it's your ease in making friends with boys as part of it. This is pure speculation, but hear me out just for consideration.

Take the online girlfriend situation for example. She probably found you were easy to talk to and get along with, and probably shared some stuff in common with you. Makes sense because if you're friends with her boyfriend, that means you two have some things in common. It's no surprise you might also have common interests with the girlfriend.

Then she met you in person and realized you're also fairly cute. (I took the liberty of checking the bog picture. I know you don't think, but modesty isn't applicable here. You're not super model stunning, but don't take that the wrong way. No one is without photo shop. Even super models. You are cute though. It is what it is.) So now you went from girl my boyfriend knows who is pretty cool, to cute girl my boyfriend shares a lot of stuff in common with, and I'm not confident enough in our relationship to be okay with that. Pure speculation, but it's a possible reason.

It could also be any number of other things. Perhaps you are overly physically affectionate? Perhaps your shyness around women because you're afraid they won't like you comes across to them as the cold shoulder? Maybe that exacerbates the situation? Who knows?

It's easy to drive yourself crazy in a situation like this one. Your best bet is to be who you're happy being, and eventually you'll create a network of friends who like you for you. It might take much longer to create, but because they're real friends it will also take much more to destroy it. If they're blowing you off, and you're fairly sure you aren't doing anything to deserve, then they aren't worth it.

(Wow, this post is like Iceglow length. He'd be so proud!)