He would retain it's unfair. But put in the same situation, he likely would have made the same call. Which of them, amongst the other Avengers, their friends, wouldn't?

It's so incredibly awkward. Natasha says Anything that might be out of place and the first word on Bucky's mind is You, but he, blessedly, manages not to say it. It's beyond insensitive, and certainly not something Natasha deserves. He's just trying to sort the disbelief and confusion.

What if she's not real? He's determined this isn't a dream, so it's not that. But she could be not real or someone wearing a disguise, right?

"Haven't seen anything like that. And how would I know what's out of place when this whole scenario feels too normal?" Which is what makes it abnormal, to him.