he wants to go party 😒

So my SO mentioned to me about how he was invited to a Halloween party. I'm kind of annoyed about how into he is going to it because I know there's going to be drugs, alcohol and girls. I trust him completely that he won't cheat. He's 19 and has never done anything bad before. Never drank or done drugs and when he mentioned it to me I told him about the drinking. I've told him before I'm not personally a big fan of it. I don't know why I'm kind of upset about it. I guess because he's always been an inside guy who hasn't done anything bad and now he wants to go out, party and drink without me it just kind of hit me like wow. I've drank and smoked and all that stuff so I don't know why it's bothering me so much. I'm sure I'll be more comfortable with it once it's sunk in. I just needed to rant a bit I guess. I told him he can do what he wants but if he fucks up its on him and that I've warned him once.Â