She looks relieved, to finally have somebody say it. To give her the excuse to sit out and not deliberately hurt herself. The permission to put her wellbeing above the mission, for once. Without it being a failure of cowardice on her part, but fulfilling a promise.

She doesn't find it controlling at all for him to ask that of her. She knows nobody else ever will. Because they wouldn't be receiving this same consideration. "Of course," she replies, swaying to the music even as the song draws to an end. Maybe she can have the second one with him as well.

"Anything for you." She knows she's stubborn and uncooperative and so used to making decisions on her own. But talking with Phil helped wrap her mind around being comfortable with allowing this. Doing things to make another happy without feeling as if she's given up her own choices. Peter's trusted her and gone along with her plots all this time. It's a nice feeling to slow down and trust him in turn.