On the subject of going through your partners gadgets. I think it not something to be considered, once you begin to consider this then I'm sure you are beginning to have elements of distrust.
It's understandable that sometimes we cannot but help the urge to go through our partners gadgets. But I have learnt that it is best not to because what we don't know cannot hurt us.

On the issue of miss x. I think 4 months is too short a period for a relationship to be experiencing these sort of issues. If you ask me, miss x should cut her losses and move on because non of the above stated reasons are enough for him to act the way he is acting. Unless there there is something else she isn't saying.

Just my opinion

Much love to @oluwatobiloba for bringing this idea to together. It's an opportunity learn from the experiences of others. God bless you