A wedding where a young quiet nerdy groomsman gets to tag along to the after party and experiences a bunch of firsts. The bridesmaids enjoy making the poor boy blush with how much he doesn't know about girls.
I was thinking a couple gets married and the wedding party are all longtime friends. The groom had a little brother who he had as a groomsman and was paired with a single wild bridesmaid. The groom teases that his brother's got a crush on his partner and all the women think it's the cutest thing. Teasing turns to flirting which turns to first experiences. Maybe multiple bridesmaids and maybe just the one. Maybe a Matron of Honor enjoys feeling young again?