What Happens In Act 2 Shadowheart Decision on a Multiplayer?

Hey everyone, I'm running a multiplayer (3 Tavs) Honour Mode campaign and we're about to enter the Shadowfell. My Tav is romancing her and has 40+ Approval, but the other 2 Tavs don't have much approval with her. My question is, when she makes the decision to kill or spare the Nightsong, what will influence her decision?