There's a couple dialogues already if you know where to look, but that shouldn't dissuade people from making further dialogues. If it had, I mighta scrapped my Minecraft-related one because there were already 2 dialogues related to the Creeper mod by Dante (even though my dialogue had a far wider scope but that's irrelevant).
For those curious about my remark above about other dialogues: f93, who already posted in this thread,
has made a Ruby dialogue. Jacob Zero (a couple posts down from this one - as of making this post it's the one immediately after this but I expect that will shift sooner or later)
has made a Yang dialogue, and oldwalkers (a bit farther down the first page of this subforum)
has also made a Ruby dialogue, but his has a more pre-defined plot (specifically designed to be Ruby and Jaune, as opposed to f93 and Jacob's dialogues). These may help guide the creation of your own dialogues for Ruby and Yang.
Funnily enough, in my spare time I've idly thought about dialogues for these 4 and my ideas were more or less in line with your own. My ideas (feel free to steal any if you think they'd work) included Yang joking about taking her to dinner first before doing this (since it would seem quite forward to just start fucking someone) and Weiss acting like she's doing you a massive favor (along the lines of "you should feel lucky that I'm actually doing this").
