What do you want out of a Romance Expansion?

Enable NPCs to initiate asking to be boyfriend/girlfriend, proposals, first kiss, first woohoo, and the played sim has the opportunity to accept or reject.

This might be an unpopular opinion, but I think Chemistry should be sort of hidden. Like, we can't tell what traits our sim will be into or not, but we can tell whether our sim is into a particular other sim or not. And then it's easier to succeed with romance interactions between two sims who are mutually into each other, but harder when one sim is not into the other.
Maybe there could be cheats to set your sim's chemistry (I know some people really like to create sims in CAS who are destined to be together), but choosing turnons/turnoffs on purpose for your sim wouldn't be the default. I hated that in Sims 2.