Some disorganized thoughts about trust
Trust is one of the reasons I think that Sartre said what he did about other people.
You have to be willing to be destroyed in order to love someone completely, you have to forego your pride and your intellect. And you have to continue to be willing even after you are hurt, and you will be.
See, the thing is that people are not "trustworthy" by the means I think most people understand. Trustworthy isn't the quality of never letting someone down, and it definitely isn't someone who does everything you want or need. In fact, I find myself wary of people who are eager to please or compliment when I feel I haven't earned such treatment.
You will be manipulated in this life. People want security, they want things to work out in their favor. They want to be trusted, too. It's so odd this relationship we have to have with others in order to have our needs truly met. We have to give in, we have to be uncomfortable, and we have to be flexible.
You cannot approach relationships with a sense that your self appraisal is true and should thus be respected and followed by all. Expecting that you will not be disappointed is not the same thing as trust, it's closer to narcissism. You will be hurt, you will be challenged, this is how you grow.
Trust is the act of opening yourself up to pain with the faith that your pain has purpose.
It functions as a door between you and others. It can be open or closed depending on your wishes.
I've found life generally more difficult when I am unwilling to trust the people around me. That doesn't mean be stupid though, I've ignored my fair share of red flags and I know I'll be paying for it for a while.
Be discerning, don't cling to your comfort, don't be afraid to rebuke those that hurt you. Forgive when necessary (usually 100% of the time), and move on when necessary (More often than you might be willing to admit.)