Thor is entirely sure how to broach Tony's lack of a verbal reaction; he feels a little like he's searching for answers in the dark. He winds up stumbling into the most obvious conclusion.

"I didn't tell him anything," he says. "I just asked him if he could do a painting for me and he said yes." Hopefully, that provides Tony with some level of assurance, though Steve could have just as easily deduced their relationship from any number of clues that cropped up since his arrival. "If you don't want him to know, he doesn't need to know."