Tbh I mostly find romances in games not that important - Dragon Age is always named as the posterchild of romances, but it is basically giving the companions gifts, do their quest and then it is 'We bang, ok?'
I would say in BG3, that Astarion is thematical and storywise really well for a good, resisting Durge, as I just found out, by romancing him with my Durge - this is really meaningful. And I say that as someone, who is not a big fan of Astarion.
I could see romancing Shadowheart with a Selunite as being maybe impactful.
But mostly I don't care too much. I like the companions (apart from Halsin) and I'm ok adventuring with them and maybe I'll do a romance - my gith mage accidently started a romance with Karlach and I just thought why not? I like her, she is funny, could be worse. I know here are a lot of fan threads discussing every detail of a specific companion and how their romance could be better and I mean props to the people, who have that kind of energy, I haven't. I would generally love to have more interactions with the companions, maybe campscenes around the fire, discussing Voss coming to our camp and dropping the Orpheus bomb at Lae'zel, ELminster giving Gale bad news, brainstorming to help Wyll with Mizora ...
It is not, that I find them especially bad or so, I don't - I did the Shadowheart romance first and it was nice - and luckily without over-the-top sex scenes, but I'm not finding myself fangirling over Shadowheart now. Or Astarion. Or Karlach. I just thought, there would be more in terms of story with romanced characters.
