there's nothing wrong with snooping. if you feel uncomfortable with their relationship, then you have to relay it to him. a lot of cheating happens at the workplace unfortunately. people spend 8 hours a day with each other and too many males and females get attracted to each other. i have too many examples of it happening in my office only. any other female that sends a man any sexual content basically tells him that she is comfortable enough to have that kind of relations. it is not proper at all. it's only a matter of time when it happens.
The male is a domestic animal which, if treated with firmness, can be trained to do most things