<human>: Just as a little background, my sister (she's currently 21) went to an out of state college and failed 3 classes, making my parents waste tens of thousands of dollars on not only those classes but summer classes to make up for that. After 3 years of this they made her come home and go to a closer-to-home college. So far, she has failed 1 class due to "attendance" (this is most likely a lie). 

On top of that, when she is at home on weekends for work, she trashes her room after our Mom has cleaned it up during the week. This room is where we keep our video games and where we work out so we need it clean for room to work out and for my mother's sanity. 

On top of that, she has recently assumed that we would be okay with her boyfriend who, by no fault of his own, is under the impression that we are all really mean to her because he has mocked me to my face. I know this is the case because with a past boyfriend she did the same thing and, when he got to know me, he was a nice guy.

This has been going on for years and years, even before college. She is a very unreasonable and stubborn person who will not change by just talking to her. My parents have even shut the vent that heats her room without her knowing, something my mom feels bad about, but she is at the end of her rope and doesn't know what else to do. They are already making her deal with a good amount of the debt but they still are taking the majority of the debt because they're good people. 

I don't know how to help this along. I love my parents and what they do for us and I don't want to stand by while this happens. As my main source of answers to questions and general knowledge, I turn to you, Reddit. Give me a hand please!

Can you summarize the given text in a few sentences?
<bot>: My unreasonable sister is to blame for my parents being in a lot of financial and mental distress and I want to do something.