I'm looking for open, honest advice, guys. Go ahead and be blunt. Thanks for reading.

Last night I was at a bar with my current girlfriend and some of our friends. (I've been dating this girl for roughly a month now and things have been going well.) At a point, a guy not in our party came up to the table and started to talk to my girlfriend and her friends. He was focusing attention on my girlfriend, pretty obviously hitting on her. I didn't step in or do anything, though, because a) I trust her and b) I felt like playing it calm was the best option, since he wasn't isolating her and wasn't kino-ing or anything. Still, I began to feel awkward because he was there for some time (~10 minutes). He gave her his number (at this point I was a little bit like, "what the fuck?"), but, after that, he left, so I didn't do anything.

I was in a little bit of a weird mood at this point. From my side, I felt embarrassed because my girlfriend just let some other guy hit on her in front of our friends, even though I was sitting right next to her; her friends seemed embarrassed, too (one of them gave me a look that said, "This is really awkward"). I suggested we leave that bar, and we did. On the way to another bar, my girlfriend asked if I was alright (she could tell I was in a weird mood). I told her the truth, that I felt embarrassed because she was bordering on flirting with some guy while I and all our friends were sitting right there. I wasn't worried about her fidelity -- I don't think she'd actually do anything with this guy. I just don't understand why she wasn't just like, "Sorry, not interested." When I told her this, she felt bad, and told me that she didn't realize she came across that way; she was just trying to be friendly. I told her that I was going to take a walk while she and her friends went to the next bar, and call her in a bit; I did so. When we met up again, we talked for a little bit about what had happened. She was genuinely worried; I can tell that she does have feelings for me and was probably just a little bit drunk.

I want to think about this situation, though, and ask you guys for a little input (on any or all of the following) about how you would respond.

1) How do you handle another guy hitting on your girlfriend when you're with her? Do you let him make a move, because you completely trust her? or do you step in and say something to the guy?

2) Did I have a right to be upset here? Or did I overreact? I wouldn't say she was full-on flirting with the guy, but she didn't tell him to get lost, either. Is chalking it up to friendliness lying to myself?

3) If I was right to feel upset, did I handle it in an alright way? or in a total AFC way? I feel as though I could have handled it much better, but I'm not sure what I could have done differently.

4) My girlfriend said she didn't think the guy was hitting on her but on her friend. Do you think this is a lie?

5) I left things with her saying that we're okay for now (she was really worried that I was going to break up with her) , but I still feel a little bit down about it. Where would you go from here?

Thanks for reading, guys.

Put your arm around your girlfriend before he approaches. This will put most guys off from approaching, apart from the most brazen PUAs.
Don't be insecure. I usually make it clear early in the relationship how I expect my woman to behave. Women are like children. They like to have boundaries. They're always testing them to see how much they can get away with. Don't get angry with her. Calmly say that accepting a guy's number (especially right in front of you) is disrespectful, but you'll let it slide as long as she doesn't do it again. Abandoning her for a while was ok, it made her feel guilty so seemed to do the trick. Was he hitting on her? You must know because you were there the whole time. Girls love attention. Doesn't mean she would cheat on you.
You are in the perfect spot now, just don't let on that you are down about it. Be clear that if it happens again you will break up. Give her a chance.

I don't know the girl at all and can't accuse her of anything, but the whole, "Are you okay?" "I had no idea he was hitting on ME" shtick is crap. She knows what she did and when you took a walk for a while, you can be damned sure her friends talked to her about it.

I hope you steer this ship and right it in whichever way you want. As suggested earlier, setting boundaries is a good next step. I personally would treat trust as something that has to be earned and not give it to her automatically after dating one month.

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"Let me ask you something. If the rule you followed brought you to this, of what use was the rule?"

Hey,

You did a great job, controlled the situation, told her how you felt, she reacted on it, it will probably not happen again, props for the great handling. If the weird feeling is there, you can't just make it dissapear and act like nothing is happened.

I've been in this situation before. And the girls, they actually see it as being friendly. While we guys know he wants to get in her pants. She said sorry, so she is a genuine good girl.
I let him make a move. I trust my girlfriend. Reacting on it, will only show my girlfrien i fear him, so his value will only rise. Not reacting is best. If i see he's the annoying type, and my gf needs to be saved, i do so.
Sure, it's a feeling, you can't hide that. It's your gut feeling, if it makes you feel upset, there's not much you can do to stop it. Only talking to her will get it away, and now she knows how this makes you feel, your relationship is evolving. You didn't overreact, i think you handled it great.
Yeah, you did. You didn't became angry, just talking to her, and thinking the situation trough. Great!
I've heard this numorous of times. She is not telling a lie.
Nothing, let some time pass untill you feel normal again. Threathening to break up isn't really needed in my opinion. She knows whats up, she apologised. All is good. In 2 days you'll be the old you.

Probably would have bothered me slightly too, though I'd have sat there eye coding my girlfriends friends and tuned it more into a joke rather than take it seriously, you handled it well!

It's when guys hit on my girl when I'm not around that it can get to me