I would be totally fine if they had made it where romance was player initiated. That's the most natural way to do it, and it basically does the same thing as a toggle option. You avoid saying or doing anything that might make the NPC think you're coming on to them and you never have to worry about it.
However, they've already created the scripts to have the characters act the way they do, and I would imagine it's probably easier to just create a toggle that turns off anything they've marked as "romance" rather than completely redo all the dialogue to make it all player initiated rather than coming from the NPC's. Only they really know that, though.
