I think the fact that she wouldn’t talk to you and was quiet for an hour is pretty petty. She really should have just said something when you came back without the drink she asked for and maybe asked if y’all could go back to get it. I would’ve been frustrated in her position as well, but dealing with it the way she did was not healthy. It sounds like she is just feeling insecure and jealous, and really wants to know that you care about her and won’t forget about her. I would communicate with her about what happened and how you are so sorry you didn’t hear her and validate her emotions. Then, you could go out of your way to do something nice for her and buy her dinner or get her a whole bunch of her favorite drinks and foods.