She doesn't have time for a relationship?

I went out with this girl and we had a great time. We went to dinner and a movie, then back to my place where we talked for a while and she grabbed my hand to hold while we watched a TV show. After I took her back to her place, I gave her a kiss goodnight and she said that we should go out again. Two days later she came over to hang out and we had decided to watch a TV show on that night. She again wanted to hold my hand and so I put my arm around her as the night went on. After a few hours, she said she would have to go and finish some reading for her class the next day. I kissed her again and we made out for a minute or two before she said she really had to leave so she could get her homework done. After this we exchanged texts for the next few days and I talked to her today and she said she didn't have time for a relationship right now. What does that mean? Why would she want to hold my hand and act the way she did if she didn't want something more than a friendship?