I would want to see romance in which companion betrays you.
Let's say you start romance with character and then at some point you're asked to do a "quest". As it turns out that "quest" is an ambush where your romantic character has proved his/her treachery.
With deception he/she just wanted to kill you and works for some evil party who wants to get rid of you.
So, romances could be very interesting and thrilling quests.
