Pretty sure my friend is the reason we're not dating, should I ask?

[ontheBUS]

Recently my friend/roommate and I have been partying with our good friends in a frat. Things were really fun until recently; my friend gets TOO drunk and becomes very obnoxious. People have begun talking about us, and now a picture of this friend's butt (taken when she was drunk) is circulating among the frat guys.
Unrelated, a few months ago this guy asked me out and said I could bring a friend. I brought THIS friend. We didn't drink, but she got very excited and talked too much and was very obnoxious. Things dragged on for a long time until the guy finally let me down. It seems strange, because he was so into me before. Now that I'm hearing things about my friend, I'm wondering if she has anything to do with him not wanting to see me anymore (she was with me every time, we never got to do one on one!!)
*EDIT: the guy I went out with is not in or affiliated with the frat, but my friend did make an obnoxious scene around him.

My other friends believe she is the reason, and now I'm wondering if I should just ask this guy. I don't want to harass him after he let me down so nicely, but I do believe this is the reason and it's been eating me up inside. Should I, and if so, how do I ask him?

[DanielR]

Why not? What is there to lose?

[ontheBUS]

I just don't want to put pressure on this guy or make him feel badly...or linger. He was a gentleman when he let me down and I really respect him...on the other hand it's been really upsetting me.

[PlayingPretend]

I honestly don't see where it'd be unreasonable to ask. Tell him you respect his decision and you don't want to come across as insulting, but that you were simply curious as to whether or not your friend was the reason; maybe even mention that you'd like to apologise on her behalf for her behaviour. That's what I'd likely do, in any case. I honestly don't see anything wrong with asking, or how it would be pressuring him any.

[DanielR]

I agree with PP, there's nothing unreasonable about wanting to know why it went wrong.

[MonsterTRUCK]

Regardless, tell your friend she is acting like a dink and let her know how you feel about it.