Even after he pulled back from the kiss, Castiel didn't let go of her, he couldn't. He had to keep holding her, wrapped up in his arms and he just couldn't stop smiling at her, back how she was meant to be. Back with him.
"I promised you, didn't I," he pointed out, his smile huge. "I will always come for you, no matter what. Even when you don't know me, you still called for me." He wasn't sure how that had happened, but he wasn't about to question it.
"I am so much better now," his voice and face were genuine as he looked at her. "I missed you. And I love you. And I am so glad you're back, the way you should be."
He reached in for another kiss, this one more playful than the last. "It's a few days late," he murmured against her lips. "But happy anniversary."