Should I leave the relationship?

I have been in an off and on again relationship with this particular female who has stood by me when i hardly had nothing to offer financially but throughout it all she is morbid obese and has never lost major weight and has major difficulties getting pregnant plus has never been consistent and we had more than actual the almost 8 years.Im going to turn 30 and I wont a normal,healthy relationship.Im tired of leaving her,fooling with some other woman and then going back to her and our less relationship.I never fully paid attention to our weird ual dysfunction until recently and i was just looking for help and feedback.I know I stay so preoccupied with like a teenager since I'm not being ually satisfied in this relationship.HELP!!!! feel free to respond here, or thedarkhadoken(youtube)