Girl's Behavior

What does it mean when a girl says she has to study instead of going out?

I have been friends with this girl for 2 years and anway. She messaged me asking if I had to go to work today because of the rain. I said yes but it's very wet, but i'm finishing early. She replied might hang later if you're round :) I then said yeah I'm around you wanna get some food or see a movie? She replied that she is really sorry but she has to study she realised. Shen then said we'll catch up ASAP she said I might be going to out tomorrow night and I asked if I wanna come. We have been to movies just the two of us and gone out to dinner just the two of us before. She also sends me the red heart emoji occasionally, puts x's in her text and has sent me the blowing kiss emoji a few times. In person she has her hand on my leg twice and when I was sitting next to her on the couch while watching T. V she pointed her knees to towards me like in a curled up way.
What does it mean when a girl says she has to study instead of going out?
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