Paranoia is hard.
It's exhausting. It's time consuming. It's ugly.
It can be hard to trust people when they've let you down. It can be hard to be vulnerable again and put yourself at risk for more hurt. But being suspicious and paranoid really doesn't protect you from being hurt again. It keeps you hurting. It keeps you in a place where you don't feel safe.
Being vulnerable is part of being human, but that doesn't mean that you have to feel unsafe.
If you're having trouble trusting someone, and you fall victim to paranoia and suspicion, eventually you will find yourself at a crossroads. Paranoia is unsustainable. At some point you have to sit down and have a good old heart-to-heart with yourself and make a choice. Even if you feel like you know better, even if it makes you vulnerable, even if it's a struggle, you just have trust again. You just have to make that decision to leave that suspicious door closed and trust that there isn't a monster on the other side. Because really, the only way to know if you can trust someone is to trust them.
Or else you have to walk away.