Even without the incredulity literally in Henry’s tone, Bucky’s perceptive enough to realize he’s started to make Henry rather startled with his initial reaction, planned or not (definitely not planned). It’s then that he lowers his pen (it had been upright all during, poised to continue drawing despite his focus on the drawing having been lost) and lifts his left hand defensively.

“I. Don’t mean any offense. If. That’s how you...” He could shove more meaningless words here but decides it might be better to just tell it as it is. “Look, I don’t know if you’re from the same world I’m from, but, uh, I grew up in the twenties. So.”

Assuming that means anything to Henry, he can likely fill in the rest of the blanks: archaic comprehension, probably never learned the normally way, etcetera, etcetera. It doesn’t really explain why modern concepts aren’t a mystery to him or why the hell he has a metal arm if he’s from that far “back in the day”, but it at least gives context to Bucky’s immediate confusion.

Which has now been somewhat cleared up now with Henry’s patience. Thanks, pal.

“So, what, you hook up with guys but only marry gals?” It’s a swing in the dark. This is clearly such a new idea to him that he doesn’t really get it yet.