Sooooooo when are they gonna kiss again??

wdym again? when did they kiss

Not not in that way...... It's like she's asking when are they gonna kiss. "Again" here is used as questioning instead of using as in literal meaning, so she's basically asking how far ahead are they gonna kiss. It's like she forgot and is asking when will it happen. An example.

" Who was the author of that book again?"

you get that