Actually I too think that Brendon is probably a really nice guy. I have no issue with him. I feel sorry for him, actually.
Rachel, on the other hand - ewwwww. For one thing, she is 100% all about her - how she feels, how someone has been mean to her, that she is tired, etc, etc, etc. Never do you see her worried about Brendon or trying to make him feel better. (Brendon, on the other had, is constantly tending to her). She is extremely self-centered.
A second is that she never takes any personal responsibility for the clashes that happen. Anyone with any life experience knows that in arguments and altercations, both sides have done things to cause them, and both sides have missed opportunities to avoid or mitigate them. Rachel, however, acts as if she is a totally innocent victim of other mean nasty people. Hogwash.
A third is that she is extremely manipulative. Surely you do not believe that those are real tears you are seeing? They are just one of the many tools in her attention-getting toolkit.
In short, I have little use for a manipulative, self-centered drama queen.