What I would love to see is system-based romance, where both your stats and dialog will factor in, when a character gets attracted to you. It's not only about what you say, but also how you create your character, which desides how the romance turns out. Some character might be attracted to strength, crafting and the egotistic trait, while perception, lore and altruism affects their attraction negatively. Of course charisma would make everyone more attractive, if you'd want to make a man- or womanizer build. Maybe you could be able to hook up with anyone, but the process would be a lot harder and you'd really have to tread lightly not to mess up the relationship.
On the surface this might seem a bit artificial, but in real life love isn't just about having nice conversations. Attraction is biological too. This would be an oppotunity to make the dialog more situational by reflecting why the characters are interested in each other. If done right, this could really make the romance feel significant.
It would also mean most builds could only have a few options to choose from. But I think this approach would really be in spirit with D:OS' system-philosophy by making the consequences of you character build affect how the story turns out and make each character and playthrough unique.
