Other forms: unaffectionately
Someone who's unaffectionate is cold, unemotional, or unfriendly. If you were hoping for a cuddly pal, you might be a little disappointed in your unaffectionate guinea pig.
You can also call an unaffectionate person aloof. They're not particularly warm or likely to display much tenderness. Your very favorite people are probably not unaffectionate, but the opposite — caring, sympathetic, and kind. The adjective unaffectionate comes from affectionate, "fond or loving," combined with the prefix un-, "not."