Re: What didn't you like about the film?
They both loved Jean, and they were both clearly devastated by her death. By X3, Logan had managed to pick himself back up and start to move on, but Scott was lost in his depression. Which makes sense, since Jean was his girl. Didn't mean Logan wasn't still hurting over it, he was just dealing with it better than Scott was. When he suggested that it was time to move on, he was trying to help.
But there's a big difference between someone you care about dying from something that was beyond your control, and someone dying by your own hand. Logan had to kill Jean, who he obviously cared about and wanted to save. They also lost the Professor and Scott. They were all devastating losses, and having to kill someone you care about is not an easy thing to get over.
Logan has never been at peace with himself over his, and he's haunted by things he barely remembers. So having something terrible happen to go with that makes living with himself even harder. The movie opens with him having a nightmare during a nightmare. It's not difficult to see how all of things can screw someone up.
"You change the world when you change your mind.