Are passwords private in marriage? It’s not etiquette to open one’s mail from the post office unless there is prior agreement. So what about passwords to all electronic communication?
It’s still private in relationships that have trust. But, when trust is broken and there is reconciliation in the works then all passwords need to be open to the victim 24-7.
If the cheater refuses, or history is erased, then the victim has no choice but to assume the worst.