I'm a simple soul. I love the italicized Oh moment when they idiots who've been pining and obvious for several hundred pages finally realise.
Also, it's not quite a trope, I think, but I'm a sucker for reincarnation romance where they actually tackle are we in love or is it just because of reincarnations and they were in love?
This particular one, I love some polyamory, especially when it's written as no big deal. But I also love One True Love. Especially if I can get them both because, you know, people who believe in both can exist in the same world, and I love when a story manages to do both naturally.