I don't think you'll get your wish.
It is quite difficult to get a BELIEVABLE romance done right in a video game. And that includes JRPG-style games where both characters involved have fixed personalities, fixed dialogue, and a fixed pacing and progression of the romance. As in, the writers need to worry about two characters (although that can go higher).
From what I can tell so far about D:OS 2, what we'll apparently have is romance options based on origin stories. There are going to be a bunch of these, so there will be a lot of possible stories which need to be written. There are a lot of variables. And this isn't a JRPG with cutscenes, so the progression of the romance won't be based on the pacing of the game, but on the pacing of the player.
There are things that could easily sell the relationship in a game like this.
The 'girlfriend' could automatically gravitate to the character, when moving.
they could have a second set of voice prompts for when they're in a relationship.
text dialogue options could have 'my love' instead of 'my leader'.
she could auto-attack anything that attacks you.
and or get damage bonuses vs anyone that attacked their loved one.
she could get grumpy if any of the npc's hits on you.
Along with some game mechanical bonuses, like 'cannot be mindcontrolled and made to attack loved one' or a stat bonus.
It's the constant small touches that sell it, not the sex scene.
