Worried that girlfriend might cheat on me at party, help

So im in a sort of long distance relationship with my girlfriend. We see each other every week once or twice and she lives a train ride away. She invited me to her birthday party, which is going to be filled with her friends (30 people or so going). I know literally none of these people, and i'd say 20 of the people are girls. But the other 10 are boys i've never met. I have to leave early to get the train home and help my grandmother. Now since she's going to be drinking a bit and there are boys I dont know there, and I wont be there with her for some of it im worried they will make a move on her and kiss or have sex with her. help please, thanks.

Why are you concerned? How is your relationship? Trust is essential in a relationship and if you don't have a reason not to text her then you should. If you're really worried, maybe you can gently express your concerns...