I've mostly had the opposite issue--when I was involved with more than one person, I was super patient and easy-going and tolerated a lot of situations that were...not that great.
I didn't have a primary and didn't want any of the three men I was seeing as a primary. I was also continuing to look for other potential dates / relationships.
So, logically, I felt that each man should be able to be himself, and if one wasn't meeting a need/expectation of mine, I could seek it somewhere else.
I was really happy at the time, but when all three relationships ended strangely in the same month, I realized I hadn't been approaching things with the right mindset.
I didn't need to tolerate problematic behavior just because I had more than one guy in my life.
Also, in retrospect, I felt guilty that I was sleeping with more than one person, so I felt like I had no right to complain about anything that bothered me.
Single, straight, female, solo, non-monogamous.