It is better to suffer wrong than to do it, and happier to be sometimes cheated than not to trust.

Being taken advantage of occasionally is the running cost of being someone who trusts, and the alternative bill is higher than it looks. A life arranged so that nobody can ever cheat you is a life in which nobody can reach you either, and the suspicion required to maintain it does more daily damage than the losses it prevents. The arithmetic favours the occasional loss.

None of this asks you to ignore evidence about a particular person. It suggests that the default be openness, with the cost priced in. Decide in advance what a betrayal would actually cost you, and if you could survive it, extend the trust and stop auditing.