Does this make any sense of what my friend did?

My friend is a really smart girl, she never gets into any trouble and is the goody-goody type of girl who follows the rules, she's never once failed a class on purpose but this year she just confessed to me that she has because she doesn't want to stay locked up in her house doing nothing and being bored and reading all the time.... she could have easily aced her math class this year but she decided against it, is that good or bad, what do you think? Everyone is stunned and shocked to see her at summer school to make up her credits... She doesn't get out much, she isn't a very outdoorsy kind of girl she is a book worm mostly so I just don't know what to think of it anymore.