awkward conversation... i feel for you. its hard getting into this shit.. im pretty new too but really you just need to chill and be yourself.

dont pick it up on FB. leave it. too much hassle for one girl. if you see her again, then go for it. i think trying to work round a bad interaction where the girl has shown no sexual interest in you is a waste of YOUR time and it can make you think too much about her... and honestly its a bit of a losery thing to do. do it if u dont give a shit and just wanna see if u can get get attention... but if u do care a bit, leave it cos it might drive you a bit needy/crazy. plenty of girls out there amigo.

if the groom wanted to intro you badly, you should have done it earlier when the party was still on and everyone was having a good time.

bang out the intro, tell her shes cute and announce to her (and the people around her) you're going to serenade her to the next love song with a cheeky grin on your face, add a few boring comments and tease her, wink and say you'll catch her later then go to the bar and have a good time with other people.

this opens it all up for you and makes the night more comfortable. she knows you think shes kinda cute. she knows you're fucking around with her and love song serenading... etc.etc. if i were you then, i'd be able to go up to her being a bit touchy feely at any point in the night and flirt. if i was in a conversation with her and others, i'd probably just fuck around and tell them "hey im gonna serenade a love song to her later... isn't she beautiful" for laughs. everyone usually finds that shit funny. aslong as u say it right, you're not taking yourself seriously but showing a lot of confidence and intent.

also its good to sometimes cut a conversation short. if its going shit, leave on a good note. nothing worse than trying to carry on a conversation when you're starting out and watch your status go from being the cool new guy shes just met to a boring motherfucker.