"We can just choose to go back," he sounds doubtful, but that opened a sliver of hope, because he's not sure he actually wanted to be here in the first place. Problem is, now that Bucky's here, he can't seem to just turn around and go look for someone to tell, 'Hey, send me home now.'

If he really can change the thing he regrets, why not at least try?

"So, why are you here? Or are we not supposed to talk about it? The thing we regret?"