It's difficult to hear the vulnerability in her voice and know he's the source of it. His dramatics are clearly hurting her. He hates that he's done this without ever realizing the consequences before this.

(Funny how her feelings are more important than his life. He can't harm another woman the way he did Peggy.)

Steve nods, unable to hold back the shiver from the sensation of hot breath on his ear. "I promise. I'm not going anywhere, Nat."