I respect the decision to not implement romance in poe1 since it is easy to do romance badly. But I think that what makes a romance good is complex, well-written characters and in my opinion the characters of poe1 are very well-written and interesting. I hope that this is something that poe2 implements. There are some very good romance mods for bg2 that illustrate what you can do with text-based romantic interactions.
I think that a good romance allows for deeper character development as you get to see a side of a companion that you otherwise might not. Though it is generally better when romances are integrated into the rest of the game so that romances feels less like tacked-on mini games. That really breaks immersion in my opinion. Also, over-dramatizing the sex and making it only happen before the final battle is kind of cheesy. I think a good romance takes a more mature approach to exploring the elements of a relationship--including love, lust, and companionship. Also, please no fade-to-black scenes to indicate sex.