She never expected him to do the little things.
Making her breakfast, buying her a gift for her birthday. Remembering how she likes her coffee. Sneaking glances at her when she's not looking. Picking her favorite movie, even though it's his turn to choose for movie night. Knowing when she's having a bad day. Squeezing her hand after she wakes up from another nightmare. Sparring with her even when he's just out of the hospital after another 'accident' with a bullet because he's the only one who can give her a fair fight.
He probably thought she didn't notice. It's not in the imaginary rule book of being partners.
But she still appreciated it.