Bolin's romance is just inoffensive, nothing great, to be honest the series never really had that great of romance, and most of the couples were just two people that liked one another. Hell, it's sad that the most interesting couple that actually had some growth between one another is Zuko and Mai.
That being said, since romance was such a small part of the original series, it wasn't a big deal.
I have no issue with Bolin's romance with Opal on paper, it's whatever. But if I have to nitpick, I would say they should have done a bit more to establish that Opal already had a crush on him (would have been a good use of him being famous as a mover star). That way when she first saw him and was taken with him, would have made more sense (whereas the way it was executed, feels sort of contrived?). Although I guess it's possible to just be infatuated by someones looks.
However, I think the lack of build up between them, and how Opal is around him kind of plays into peoples fears that she is playing him (because it doesn't seem natural). It's another example of the writers being kind of stilted at this sort of thing. But on paper, their personalities mesh.
Oh another nitpick, I hated how they made Bolin a douche (prior to him falling for her). It then makes it out like, Bolin doesn't really like Opal for Opal. He only likes her because she wants his D (literally, that's how that bathroom scene came across as). And I found that shameful (it was a small little scene, but it really was a bad moment for Bolin). It also kind of undercuts their romantic moments, because it feels like Bolin is only into her, because she's..into him (and that's just lol douchey, I'm sorry). And this of course plays into the larger narrative of Bolin and his romance's never being taken seriously. It's like, Bolin just falls in love with whoever is willing to give him a second look. There isn't anything inherently wrong with that personality (people exist like that), but I dunno. It doesn't really work for me, personally. Because then why do I actually care about Bolin and Opal (or whoever he currently likes), if it's just an infatuation and nothing of depth to it. She's just another flavor of the season for him. bleh.
OKAY so maybe I do have some issues with it afterall.
Let's just say, I don't hate the idea of it. And if they do decide to flesh that out more, I'm okay with it (because I like her personality, and I think they could have chemistry based on their personalities). So I'm cautiously optimistic. But haven't been a big fan of how they set it up.