He sees Natasha's dark eyes widen a fraction as she takes note of the endearment, followed by a look of understanding and sympathy. She moves out of the way so that Sam can take a look at Sharon, and comes over to his side instead.

"James," she murmurs. "Give her some space for a moment. Let him work." She turns a level look on Steve, who holds it for a second or two before he nods.

"I'll go check on Tony and Zemo," he says, flattening his hand against Bucky's back. "Wait for me," he tells him, and lopes toward the back of the jet.