How do I learn to trust people?

How do I assess my own mistrust?

If I have a bad intuition about someone, how do I determine whether it’s sound or whether it’s just my own considerable issues with trusting others? Every time I have trusted someone it has been a mistake. Every time I haven’t, I’ve been proved right, eventually. Therefore, isn’t it rational not to trust anyone? One can always find reasons not to, if that’s what one is looking for.

NO, THAT’S NOT RATIONAL, because it assumes that the same pattern will repeat itself indefinitely, which is unfounded. It’s possible that you’ll meet someone else who you will or won’t trust, who will end up meeting your standards of trustworthiness.

I don’t know if your perception is distorted. Maybe you’re meeting mean people, or maybe you’re blowing things out of proportion to protect yourself from being rejected/forgotten/belittled. The good news is that my advice is the same in either situation—talk, and equally important, listen. When someone breaches your trust, tell them without attacking them. Explain what offended you and how you see it. Let them say their part and then wait. At first your instinct will probably be to fight and defend, but after a little bit, you’ll actually start to listen to one another and you’ll have a chance to examine what happened without being so emotionally charged.

If you change your mind, that’s okay. You now have a little insight into your distortion. Make a note of it, but don’t beat yourself up, okay? Trust is at the core of all spiritual disciplines. It takes time to work on and it’s a challenge for everyone. You’re aware, so you can (and must) nurture it. It’ll happen slowly without you realizing. 

P.S. Don't blame yourself, really. Sometimes people absorb sensitivities from their parents.