You asking if she doesn't want to share a bottle with others is, after all, a reply to her saying she wants to wait with sharing it until the others are asleep. Another implication that she wants to share the bottle (not anything else) with you and not with the others while the party is still going on.
I think it's deeper than that. Try streaming this movie - it's fantastic movie where people are talking about personalities, psychological struggles and relationships while ostensibly talking about wine. Here the MC is talking about his favorite wine but his date is savvy enough to figure out that he's talking about himself:
