When Crowley pulls back first without responding, Aziraphale gets the immediate impression that he did something wrong. That he said it wrong, at the wrong time, that he got the wrong impression, that it was wrong. It's a lot of ways to think something as simple as words and as heavy as these are wrong, in a mere couple of seconds.

But he sees the look in Crowley's eyes, how they reflect the dim light. Their hands are still on the angel's head and he isn't quite sure what that means. The music misses a few notes and plays entirely out of pace.

"I, hum." He stutters. But it isn't wrong. Can't be wrong. It's not. The time is right. As right as it could ever be. The words are right. He's said it. He's said it.

This time, he holds their gaze. "--I love you."