I've realised and told myself that "if you go searching, you will find something".

What I mean is, if you convince yourself your partner is cheating/being unfaithful and start going through their stuff, you may find something - but because of your pre-consumptions, you have already taken it out of context and made a scenario in your head that won't be shifted. The thing that you find may have a story behind it but you will be blinded by your own thoughts.

I've accepted that everyone has their own lives and I don't go searching or investigating - but this is my solution and it is very personal.