<human>: Give me the gist of the text in a nutshell

I'll try to keep this as simple as possible but bear with me and Im sorry for how long this is. My girlfriend(22) and I(22) have been in a relationship for a little over four years now. We met in high-school but started dating in college and everything has been going really well (talking about long term plans, marriage...etc). 

She is one of those girls that tends to have more guy friends than girlfriends and I have never had a problem with this because most of them are really awesome guys.

While I was studying abroad last year she grew pretty close with this one guy, we will call him Matt, who obviously had feelings for her. For the last year or so the running joke around her friends has been about how much Matt loves her and is eventually going to make a move on her. He tries to call her pet names like "love" or "babe" and she has done a pretty good job of telling him to stop every time he says or does something inappropriate like that.

Long story short a few weeks ago he got drunk and openly professed his love for her. She sat him down and tried to tell him she is happy with me but that she still wants to be friends with him. I guess that night he got wasted and hooked up with another girl.

When I heard this I thought great he's moved on and eventually everything will get back to normal in that group of friends. But my girlfriend was pretty upset that he hooked up with someone and said something like "it was a rebound and not fair to the girl."

I feel like my girlfriend is taking this whole situation with matt harder than she should. I'm starting to think that their relationship was much deeper than I knew about and my mind keeps thinking that it was almost emotional cheating on me.

Am I crazy to think this? I don't want to tell her that she cant be friends with this guy but at this point I cant see any other way around it. She knows how Matt feels about her but she still wants to be friends with him. I feel like I'm stuck between a rock and a hard place. what should i do?
<bot>: My girlfriend's friend professed his love to her, she still wants to be friends with him and got upset when he hooked up with another girl.