Some of the Avengers had just come back from a mission and are sitting in the lounge, quiet. Bucky just came back from a walk when he stops at the entrance of the common room, making sure he's not seen, listening to the conversation.

Sam: "How are we gonna tell Bucky?"

Natasha: "We're not."

Steve: "We don't even know if she'll make it before we find her from HYDRA."

Bucky remains quiet, an expression of anger and fear on his features as he puts together the pieces of the puzzle. You must have been kidnapped by HYDRA. And they weren't going to tell him. (Bucky's your boyfriend.)