I only found out because I noticed that their bios had changed. I knew they'd be fighting at the keep while Jenny was on a quest, but I assumed I'd play that battle, too. But it happened without me, and the game didn't tell me. I never got a chance to help them. It was Alistair dying all over again, except this time I didn't even know until it was too late.
I completed all the upgrades to the keep. I left four people in my party behind. I did what I was supposed to do but it wasn't enough.
I wonder if the Architect played me. I still don't know why any of this has happened. And Anders is dead.