Friendships

Don't know if I'm in the right place but I need to talk about it and there's only so much my friends can listen too before they get tired of hearing it. My bestfriend also my roommate have been having some problems. We have a great week or weekend and have normal conversations and then something happens and she snaps and then we either don't talk and she goes to her boyfriends house or she barely talks to me. Then a couple days after she'll talk to me like everything is fine. I don't know what to do anymore. Yesterday she asked me to cancel on other plans I had for a week so I could go to dinner with her and she got mad when I said no. So yeah I don't know whats going on or what to do anymore