When you are in a relationship, the most important thing is trust. You have to trust your other half else there's really no point in being together.
Ah Dear trust me, and I trust him back. I know what he does, he volunteers information and puts me at ease all the time. He knows what I does too and I would let him know if I'm going out with anyone.
Our trust goes to the level where he knows all my passwords, I'm not worried that he will go into my account and start checking on me, he can go ahead and do that coz I have nothing to hide.
We keep our hands off each other's mobiles too. I feel that one's mobile is one's private property, and it's just stinks to go checking someone else's private messages. If the person really have something to hide, do you think you can find it?
So Ah Dear's mobile is left alone unless I wanna play games. My mobile is also left alone, unless he wants to take photos.
Also I feel that when you start checking on your other half, there is something wrong with the relationship. I once heard this, "you will never suspect if you're not cheating." I really think that it's true, to a certain extent of course.
If you don't cheat, you will not think that you're partner will cheat, it's just a mentality. Whereas if you yourself cheat, you will start wondering if the other person is cheating on you. It's human nature. If you don't do something, you would not think that the other person is doing that very thing.
Of course there are cases where it's easy to tell when the other person is cheating even if you are not.
But I still think that a couple should have trust. Learn to trust each other and give each other benefit of doubt. Why make life so difficult and start checking on each other? Checking their mobiles.. This is something that I will never do.