Why does it seem that all the bad relationships make it the distance?

[RichJenkins]

I have known over 10 couples that grew up, formed and matured in high school as I did with my girlfriend as well. However, we were together for 3 years and now currently on a break. What I can't seem to understand for the life of me, is why almost every other couple has made the grade, handled long distance, and still survived when they fight constantly, get in arguments, are very unhappy at times, and seem to constantly flip out over nothing, whereas my girlfriend and I had an almost perfect relationship, never fighting and always happy. I find this very frustrating, is the stupid arguments and fighting somehow what keeps the relationship alive? It doesn't make sense, doesn't seem fair.