Most Helpful Girl
The other users pretty answered the first question. As for the second question it's simple. They were looking for a way out. The person wasn't happy with the relationship so when an issue comes along that a normal couple can work out this "petty reason" gets blown out of proportion so the unhappy person can get out.
Most Helpful Guy
I broke up with someone who truly loved me so I can give you my opinion on the matter.
In my case it was the fact that I wasn't happy within the relationship. Even though someone really love me and all I still need to think about myself. What I asked myself before the breakup "Is it worth sacrificing my own happiness just to make her happy?" and the answer to that in my eyes was no.
A good and healthy relationship should be one were both people are happy with the relationship and if they aren't compatible for some reason then I say that is enough justification for a breakup