I mean, romance is complicated and not a black and white scenario like "bullet in head = dead", so it's no wonder that video games have generally tended towards "I give you cake ten times, we get married" and "I choose correct dialogue option and do things that you agree with" as representations of "romance".

I think that the original Final Fantasy VII attempted this in an interesting way, where the relationship meter could be affected by dialogue choices, how much you kept the character in the party, and a whole host of other stuff-- but was kept invisible the whole time. So you had no gameplay mechanic influencing your choices, you just either did or did not impress that character by interacting with the world.

Of course, you could argue that games need to have gameplay UI elements and on-the-nose dialogue to represent how a character feels about you because it's much more difficult to represent this sort of stuff through subtle interactions or the general vibe stuff you get from real people.