When you've been let down, what does it take for you to trust again?

Do you 'ice' the person in question?

There is a huge difference between trusting someone again and forgiving someone. Love is always free, but trust is earned.

I cannot blame them for what I do with what they do to me. I am responsible for how I respond. Henry Cloud

We cannot keep the birds from flying over our heads, but we do not have to let them build nests in our hair. Martin Luther

For the quadrants above (by Robert Fisher):
Suspicious still: Don't ever trust anyone, even after they have done something nice.

Suspicious until: Don't trust anyone until they prove themself.

Trust until: Trust people until they screw up.

Trust still: Trust people even after they make mistakes, sometimes even when they hurt you.