Think about your friends on the Left - are they tolerant of people who aren't for gay marriage? Or of people who are pro-life? These used to be just political differences, and now they are a referendum on what type of person you are and whether you can be in someone's life at all.
Sadly, the Left is no longer liberal at all, for it has traded in individualism for collectivism, thus placing us into an oppression Olympics where victimhood is a virtue. This post-modernism - this cultural Marxism or whatever you want to call it - can only destroy; it cannot create.