Wow, the insinuations regarding the OP are just not appropriate here.
This is a serious matter, and is not just that she seems to be easily annoyed.
If memory serves, the OP seems to have just the OPPOSITE issue, being in situations where the others involved seriously disrespect her. Maintaining situations where she is subjecting herself to some serious negative repercussions.
OP.... I am not sure if you will understand this, or be able to do this... But, very simply, you need to call the landlord in.... If you do not alert them to this, you are liable, you are 'complicit'.
Perhaps they will relieve your roommate of her lease, and allow you to find another roommate. (and, I am not assuming that your long-term but always 'distant' boyfriend/fiance is the one)
Can we assume that you would like to stay where you are at?
Are there any options where you may be able to find a small place on your own?
If this is like previous threads, I know that you just want to vent, and may not actually be willing or able to take any action. But, all we can do is try to tell you what should be done, in YOUR best interests.