"Does it really need saying?"

Seeing Rose kiss the duplicate of him had been on the hardest things to watch. He wanted to be the one she kissed. He wanted to be the one she grew old with.

But he never aged. She could spend the rest of her life with him but he couldn't. The duplicate of him could though. And that gave him a sense of comfort.

Rose Tyler got her happy ending.

Maybe he didn't but he only cared about Rose's safety, health and happiness. And if Rose was happy with the Meta-Crisis, then he was happy too.

Since he couldn't be with her, he had given her the next best thing. It didn't make it any easier to leave but at least this time she wasn't alone. She had another him to next his place.

But knowing Rose, he knew no one could take his place, but his duplicate could help fill the void. She'd have him while he had no one. No duplicate Rose. No one.

He wasn't sure if he wanted another companion. After erasing Donna's memory and leaving Rose again, he wasn't sure how he'd take to another person traveling with him.

In all honesty, he just wanted his Rose Tyler back. But he'd never get that again.