Below quote from your post is mostly happened incident. Some of the cases end up with relationships break up. Thanks for sharing nice topic.
I remember one day a friend of mine was so burnt on checking out his fiance's whats app messages because he had suspicions that she was going out with another guy... On consultation, I was very clear about the matter, I told him to respect the lady's privacy and even if he had the chance to look he shouldn't as this has far reaching consequences....