I've heard the exact line that one of the other mama's used on me by my husband about a million times. The line is: It's not that I don't trust you, it's everyone else I don't trust.
That is a lie, not only to me, but to himself as well. He doesn't intentionally lie to me about this, he believes it's the truth. He knows he's screwed up in the past. A lot. He believes in karma. He truly thinks that he has a boatload of pain & hurt coming to him directly by my hand.
If he was able to be honest with himself, he would realize that he has taken all of the wrong things he has done & projected them onto me. What happens then is he thinks it's fine to watch me like a hawk figuring eventually he'll catch me doing something I shouldn't be. It's not a fun way to live for either one of us.
If either one of us was to have trust issues, it should be me, and I did for a good long while, rightfully so, but I've moved past it. I've learned from it. I've realized that if he's going to stray, me being my own personal detective isn't going to stop that from happening. I've made a conscious decision to stay in the relationship, but to listen to my gut. If it tells me something is wrong, I KNOW it's right, it always is. Until that happens, there's no sense wondering what if, checking his phone, reading his emails, etc. etc. etc. I've chosen to live a peaceful life & deal with whatever comes my way WHEN it comes my way instead of looking for trouble where there isn't any.