Guy(M21) asked my Girlfriend(F20) to hang out ALONE

Our Relatioship

My girlfriend and I (M21) have been together for four and a half years. We started dating during my senior year in high school (she was a junior). Well she went away to college and we've been in a long distance relationship for a while now. We had hardships, but we stuck through it and it has made our relationship stronger. We made an effort to see each other as much as possible.

So what happened

Well today one of her guy friends asked her to "HANG Out" on saturday night. Just the two of them, he is buying alcohol and they are supposed to watch the movie Thor (WHYYYY). I trust my girlfriend, but I do not trust the guy. I'm certain he is trying to score with her. So I told her that I don't feel comfortable with her hanging out with him ALONE in his apartment on a Saturday night. I didn't tell her she can't go. I'm not forcing her to do anything. Am I being too paranoid? Now she's thinking that she might not go anymore.

TLDR

long distance relationship, her guyfriend asked her to hang out alone at his apartment to watch a movie and drink. LATE NIGHT. WHICH IS TONIGHT! posted this last night but got removed since i didn;t put TLDR