The fact people could, in theory, create both protagonists with the same gender does complicate the romance content too although if you can't take a hint from the game's box that's one's own fault. Maybe they were afraid of ending up in awkward land if family members played coop and faced the romance discussion(s)? Again, that is peoples' own fault if they can't take a hint from the bloody box and load screen and every other piece of information about the game.....hell, it's in the bloody title...."Original Sin".
So you connect the term "Original Sin" with romance? Interesting...
Not completely but the cultural association is there in most western cultures....especially when coupled with this:
That's called take a bloody hint and go pout somewhere else.