This is interesting, I have recently been wanting to check my partners texts as he has become very protective of his phone, keeps it on silent, does not let it leave his side and will be texting away but as soon as I walk in he starts deleting texts. I have checked his phone and found photos of girls from prior to our relationship commencing, he did delete them after I confronted him but has since had a go at me for invading his privacy, the way I see it is you shouldn't have anything to hide and if you do there is a problem.

I couldn't care less if he checks my phone, social media or whatever, i am loyal, open and honest and have no secrets, I wish I could say the same for him.

In my experience if you are raising this question and have any doubt then go with your gut feeling.