She was a little kid infatuated with the cool brooding figure in the class. Once she got to know him, she realized there was a lot more to him than just looking cool. She also began forging a bond with him during their time together as a team. She fell in love with him as a kid and hasn't been able to get over him. She tried to understand him and break through to him. Is it irrational? Sure. But its just about the realest feelings of love that you can have at that age, so I wouldn't call it shallow at all.
–- Update From New Post Merge ---
I mean obviously if you can't identify with her original feelings then none of the subsequent actions would leave you with much of an impression. I took it as a young girl's first love who she can't get over. Also, Sasuke reacted to her speech when he originally left the village. They weren't emotions of love most likely, but it did show at least an acknowledgement that her words could affect him. Also his "thank you", which was honestly a lot of emotion shown for him at that time haha
Umm what bonding did she do with Sasuke that helped her learn more about him as a person? And not just a blood thirsty revenge wanting "hotty"?