Have you ever stopped being friends with someone over differences in political views? Are there any issues that are so important to you that you cannot be friends with someone who holds a contrary opinion?
The only people I've ever deliberately "stopped being friends with" were those who wouldn't leave me alone on some political topic. Not because we disagreed on the topic, but because they wouldn't shut up about it. I've got better things to do with my time than be harangued at.
For what it's worth, I've taken to avoiding people who won't shut up about issues where I agree, too.
Most of the topics that would be important enough to me to break a friendship over are pretty basic, like "Is rape okay?" "Is murder an acceptable way of dealing with an issue?" or "Is genocide good for the economy?" But stuff like whether the demidupes or pooblioobs are in office? No way.