Well, I've managed not to romance anyone in my dark urge run where I've tried to recruit Minthara.
Maybe it depends on the approval score and when you have conversations with companions. The game kind of stumbles over that, because one act two DU scene is clearly written with a romantic interest in mind. If your character has no lover, it grabs the companion with the highest approval. This doesn't quite work, because approval means they like your character, but not necessary that you like them, so the scene ended being unintentionally funny.
