You can tell by how he reacted to the other girl's hug how comfortable he is with her all up on him. If he welcomed it or allowed it to continue, she probably does this more often than you think when you're not with him or around his youth group. Fellowship just brings out the horny and the crazy in teenagers. I'd be asking some questions.

Okay, guys on here: I swear, we are NOT all batshit crazy!

Be careful dating within a youth group.

Last time I went to youth group at a church I was asked to leave for kissing my gf. Then my parents were called and the pastor had a long talk with them... I don't go any more lol

Punch the bitch

It's called back the hell off or someone's getting hurt and I mean you

Thou shalt not be a asshole

I would've told her straight up to back off or get shanked. Had to do that with my boyfriend before....thankfully he thinks it's funny when I do.

Slap her.