Suspecting everyone keeps you safe from betrayal and also from friendship. That’s an expensive security system.

Total defense works, and it works on everything. A posture that cannot be exploited also cannot be reached, so the same wall that keeps out the people who would hurt you keeps out the ones who would have stayed. Most people arrive at it honestly, after something that made caution feel necessary.

It does not have to come down all at once. Pick one person who has given you no reason for doubt and extend slightly more than your rule allows, in something small. If it goes badly you have lost little, and if it does not, you have evidence the rule can be edited.