<human>: Can you give me a shortened version of the text?

We're both 18, in a happy ten month relationship. Throughout the school year, there has been a really squirrely guy discreetly trying to get at my girlfriend. I feel like I need to address this issue with either "that guy" or my girlfriend. Who should I talk to about it first?

A couple examples here. The 3 of us are in a choir group at our high school. That guy, I'll refer to as "L", would take my girlfriend to one of the practice rooms off to the side and talk to her privately. I found out from my girlfriend that he was revealing to her his struggling life story as though to get her sympathy. I didn't worry at all and brushed it off. Later, though, I find out he asked her out to lunch, and she accepted. I brushed this off too; it's innocent. But... these little invites continued. And it's now at a point where I'm not cool with it. The other day they were up talking at 2am on Facebook IM. My girlfriend is out of town. "L" told my girlfriend that since she's been gone, I've been moping over her absence; it sounded like he was trying to make me sound weak. It's at the point where I have to do something. My girlfriend says he's not a threat, and mind you the guy is avoiding me, but I want him to stop being such a punk. That's enough. Do I confront the guy about it or tell my girlfriend I'm not cool with him intervening all the time? This is my first (and hers) deep relationship and I've done my best not to be controlling or unreasonable. Any advice is appreciated.
<bot>: Guy is sneaking into my relationship with my girlfriend. She says he's not a threat, but he's intent on having her. It's gone a little too far imo, and I don't know who I should confront first.