I can honestly say that this is the strangest question I think I've had here on Guyspeak. And truly, I'm unsure what's going on here. But you can't ignore patterns. Maybe it's not that you're picking the wrong dude, maybe they're picking the wrong chick.

Can we be honest here for a second? Good.

If a dude is really feeling you, there's no way in Hades he's going to "pass you off" to his best friend, or anybody else for that matter. Especially if you're hot. But more importantly, most guys would never do that anyway unless they absolutely had no interest in a chick - like ever, or were douches and had already slept with her. At which point he realizes the chick is disposable (harsh, I know) and wants his homeboy to have a crack at her (again, I know, harsh).

I'm going to assume that all of these guys are totally exclusive from one another - basically, none of them know one another - so these are all totally random experiences in which case, I'd suggest you do some serious soul searching and figure out what it is about those guys that you liked and what they seemed to like about you and find out what went wrong. The first time a dude attempts to hook you up with his friend, okay. It's happened before. Sometimes, nice guys realize you're a better fit for somebody else and believe in love and all that flowery stuff. The second time would give me pause. The third time? I'm calling shenanigans. Something is awry and foul in the state of Denmark.

Did you end up dating any of the "best friends"? How did that go? Point is, this is a clusterf**k of oddity and I'm unsure as to what exactly is going on, but the one common denominator is you and you need to evaluate what in the hell is going on here with you as well.

That might be the longest, most non-helpful answer ever.