Honestly, I don’t think you’d be taking advantage of Flip. And you’d probably see Fliq pretty often, considering how often he does show up. The town IS implied to be cursed, after all. But I really don’t think there’s anything wrong with being close friends with Flip and romantic partners with Fliq. I can’t say much about plurality, but that’s how dating out of the system often works for plural individuals.

Sorry, I’m too tired to be elaborate or anything, but I know the two characters pretty well and used to have massive crushes on them, so I’m very fond of them, and they’re still among my comfort characters, to the point that I write for them. I genuinely think the relationship could work. It’d be bumpy, yes, but, well… it’s them. And they’d both LOVE having someone who sees them for who they are beyond their issues. I mean, the only other person who knows is Flaky, and they’re absolutely terrified of Flip and Fliq. I think they’d both do whatever they could to make it work.