He gets that she is. He'd smelled the older (former) vampire's scent in that place, though he regrettably admits that he didn't even notice it or actively sought out any signs of anyone else familiar until after Drusilla had said they. Cordelia and Godric, two people who'd played a vital role in Angelus' defeat. She'd had the vision of his soul being restored and Godric had taken him back to the hotel after River had taken him down. Angel knows why Drusilla didn't go after Dawn, despite the teenager being responsible for the actual re-ensouling via the gypsy curse, for Drusilla was fond of her. It was why she hadn't allowed him to kill her when he was Angelus. River, though... He doesn't understand why the girl wasn't targeted. She got off easy, whatever the reason.

"It's not that simple, Cordelia." Angel leaves it at that, for he doesn't want to fight with her on the complicated subject that is his creation, especially after what Drusilla did to her. "But, you're right. I can't do it. I wish I could and I want to, for you, but I can't. And I hate myself for it. But, I can't ignore her, either. She's my responsibility and I'll...figure out some way of dealing with her one I can think straight."

Which, in Angel-speak, means once he can think of something that doesn't involve going on another rock star trash fest in retaliation for being so unable to do anything about a situation that was now over and done with. He hadn't even noticed she was missing until Wes pointed it out. Maybe if he'd caught on sooner, Cordelia (and Godric and the others) could've been spared that experience. He should've noticed.