How to make an upset girlfriend happy?

Give her a big hug that lets her know you'll be strong for her when she cant be. When you hug her put your arms around her waist and lift her just enough so u have to look up to see in her eyes then kiss her slowly. When u put her back down don't let go. Hug her for a few more seconds kiss her on the forehead and grab her hand. Really there is no need for words. Let your heart talk. Then for an added touch make her dinner have her watch. Its nice to watch someone do something special for you. She'll know that you understand how she's feeling and it might take a little stress off her.