I constantly doubt my own judgment because I see BPD traits in so many of my loved ones. I know it's supposed to be really rare though, which is what makes me think i'm crazy. I know a lot of times we attract people with Cluster B disorders so I wonder if that's why? 

For background info, I've had the same friends/ close relationships throughout most of my life. My newest friendships would be around when I graduated high school, so ~3-4 years ago. The reason I'm able to maintain these friendships is basically by never talking to them. We are there for each other because we care for each other, but it's not like we make an effort to see each other unless there's a special occasion. I know for sure one of my best friends has bpd. However, I constantly notice signs in my other close friends. I don't want to diagnose them or anything. I just wonder if it's a common occurrence to  know others with bpd by chance; we connected because of our similar beliefs/ thought processes after all.