I don't see how I'm making it about me...
OK, I'll tell you how. It was right in your OP:
"So now I have the dilemma as the boyfriend of what to do. Part of me wants to simply end this guy. While I don't see my girlfriend as property, you simply do not make a move on another guy's girl. And when you do, you should face some sort of consequences. I just don't know what to do, but feel I should do something. If I do nothing, he'll assume she didn't tell me, or that I'm too weak to confront him. If I do confront him and end up kicking his ass, we've got legal and criminal issues to deal with. There's got to be something in between, and I'm not in a state of mind to figure it out. I'm pissed at this guy, and a little mad at her for putting herself in that situation...but mostly just pissed at him."
How is that not about you?
I don't mean to criticize you exactly - your feelings are really natural, and speaking as a woman who rather likes protective males (at least in judicious doses), they're not wholly unattractive feelings either. But it's important that you recognize them for what they are. No doubt you also have feelings of concern for
her, for how this will affect
her, for how this made
her feel...but your first feelings, at least the first feelings you posted here - and forgive me for making assumptions, but I really do believe they were your very first feelings - were about
you. Recognize that, accept it, and try to adjust your behavior and even your thoughts accordingly.
Because this guy didn't do anything to
you. I know you feel a personal sense of injury here, but it really and truly is not justified. He did whatever he did to
her. And you really, really, really need to realize that.
...and I never said I would be the one reporting him. I know she would need to be the one to do it, I would simply suggest that she do so. I agree she needs to get over her fear of confrontation if it does become necessary for her manager to become informed. I've stayed out of it thus far, for example not saying anything to him or being a jerk when I met him at the store. If he does continue to pursue her, though, it is going to be hard for me to stay out of it but I'll try.
Ah, good. It sounded like you were taking ownership of this issue, including ownership with your GF's employer, but if you're not, so much the better. But you really do need to let your head and your good sense and your respect for your GF overrule your hormones here. Really. Good luck. And good luck to her, too.