Haha, I remember playing the Magi Origin as a female and I was able to tease Cullen a bit about bedding him (even teased him more during the Broken Circle quest). Instead of being pious and refusing outright, Cullen scurried off nervously about the proposition, made me wonder if he'd do the dirty. When looking back at that and his his involvement in DA2, it seems it was possibly laid out to make him as an LI now.
My flirty Surana teased him also at beginning, though she might had felt teeny weeny badly about it when he was so tortured about his crush.
Then again, mage in question did bed all possible members in her party and still felt bad hurting their feelings - she was rather complicated character and ended up possibly insane.
Anyway his character arc has potential, alot.