Problem with choosing the Dark Urge Ending in Coop

[spielemeister]

I have the following Problem, i started a Online Coop Playthorugh with a Friend and picked the Dark Urge background for the corresponding Trophies (he did not pick Dark Urge). While playing thorugh the game i did all things needed to become Bhaals Chosen but at the end of the game after defeating the Netherbrain the Person who got to decide the ending was his charakter and not mine. I'm not sure why, maybe it was because he also did a lot of dialogues, maybe more than me over the course of the game, i'm not sure. So now i can't finish the game with the Dark Urge Ending because my charakter literally can't make the decision. Is there a way to work around it? I tried to load alone into the game becuase i'm the host and also killed his charakter off during the fight but at the end everyone is alive and he gets chosen everytime. Is there a solution or do i have to do another full Dark Urge Playthrough?