I don't think it's about alcohol at all, it simply doesn't make any sense - if you have one beer on Monday, what does the next beer on Wednesday have to do with alcoholism, safety or health? It's just about you spending time with your buddies, having fun without her, leaving her alone and whatnot. It's selfish and controlling and you should put your foot down. In a healthy relationship both partners should be able to go out with their friends and have some sort of a private life. Maybe it's jealousy or insecutiry or whatever but she needs to accept you want to be alone with your friends sometimes.