Your girlfriend is being nice by leaving a little for you! You should be grateful that she does that. You do the same for her
My girlfriend always ends up leaving a bit of her dessert and always says I should eat it what does she mean by it?
She is trying to fatten you up maybe
She wants to share with you! It may be a sign of affection, something she can give to you.....kinda like saying "I love you" something she only does for you. In those terms it's kind of endearing! Or...she's just full! Lol!