Story time everyone. This is a sad/depressing one.

So yesterday I was at the beach and I noticed this girl and her friend next to me. The one looked 14-15 and the other 13. After a while I noticed her staring at me a lot. She and her friend were whispering to each other and I think she liked me.

I didn't know what to do and I saw her friend trying to get her to talk, but she didn't. After a while they left and I felt instant regret for not taking the opportunity to talk to her.

Except one thing: I can't talk to girls unless I'm smashed. How do other guys do It? Maybe I'm too socially autistic to do anything. How do I do it r/teenagers? (Keep in mind that they're mostly in a group so it's even more daunting.)