I've been married to my husband for 5 years and we've been together for 11. we have done some really awful things to each other in this time. Like soap opera awful. I am surprised I am still married sometimes, I have the greatest husband because he puts up with me I hope your difficult girlfriend realizes how hard she is to deal with, and loves you even more for it.
She may not, it took me until recently to realize how good I had it.