I have been in a serious relationship for the past five years--my only real relationship actually. My girlfriend is without a doubt the best friend I have: I can talk much more easily than other people, and we have a degree of comfort with each other that I don't have with others. We have trust, care, and personality compatibility.
We have problems, though, such as her being excessively depressive (she has major depression, compulsive overeating disorder, and avoidant personality disorder, but refuses to see a therapist) and ready to lay blame, and our parents create serious problems for us. She is also moving 400 miles away in a couple of months.
The biggest problem, though, is that I am just not sexually attracted to her anymore. I feel shallow for this, and wish that I did find her attractive, but in the past two years, she has gained over one hundred pounds due to her cycle of depression-binge eating-greater depression-greater binge eating-etc. And she is still continuing to gain, despite trying to go on diet after diet. We still are able to have sex, but it is less frequent, more labored, and honestly, I think about other people when we do it, and I use porn a lot (she knows this). And we're only in our early 20s.
Sex is not the only concern I have relating to her weight gain--her current weight puts her in class II obesity, meaning she is at high risk for serious illness early in life--so I fear that she won't always be around, or at least not in any condition to enjoy life.
So, my question is, should I break up? I don't want to lose her friendship (and I know I will if we break up), but I just don't know if continuing with this is the best investment of my life, time, and energy. I am generally energetic, but feel weight down by all of this. And I don't see any likelihood of the situation turning around. This combined with her emotional problems really takes a toll on me. At the same time, I really do care about her, and would feel horribly guilty if I ruined her life.
Any help or insight would be most appreciated. Thanks