All I can tell you is from my own tainted experiences and ideas but try to break things down as simply as you can...the truth is, no matter who the other person is, we never really know what they are or aren't doing. This is because they are not us. The only people we can truly know what they are doing is...US. Ourselves. We can only change ourselves. We can only know the truth about ourselves.
There are many exercises designed to help couples rebuild trust but the fact remains: we never actually know...so therein lies the next step: if we choose to be with our partners who have conclusively shown themselves as untrustworthy, then we must let MANY things go. For real.
As our partners do their part to rebuild trust and show remorse, we are forced to take a journey as well. One that involves understanding codependency, boundaries and the difference between feeling like we have trust and a tight relationship based on how we feel about the other person, rather than the truth of the matter...that people screw up, cheat, make mistakes and do horrible things to loved ones and many people either don't know what they will do until they run into it or they have poor boundaries, often because they never really understood they needed them or never thought about it.
All kinds of crap happens for all kinds of reasons. My point is...it's more about what you choose to do with things.
Example: I used to give my husband no verbal, clear expectations because I thought we were on the same page. I thought we had the same goals, dreams and love. i learned rather quickly that not only were we not on the same page, through time, we weren't even in the same book.
After a long separation, I gave him clear expectations. Not many but clear ones...you know what? He did whatever he wanted and it culminated in the worst debacle to date and trust me, there have been many.
This (last) time around, I make NO demands. I let him know my feelings about specific things and we talk a lot. Here's the difference: I have told him that now he knows what I want and don't want, I make no demands but if he wants to be in my life and live with his children, our ridiculous pets, and be a part of our artistic, crazy, close family...he will make the effort and we will accept absolutely nothing less. I tell him 'you do whatever you want to do' because my demands never mattered. What mattered was me being willing to lose him, telling him to go and walking away.
I don't know, if after all the years, it will be worth it. Our MC asks me why am I still with him and honestly, I'm still working out those details and I'm still suffering bouts of rage beyond comprehension. I think to myself 'after you've wasted so much of my life on other women...so much of our kids time...why AM I still here? I'll get you to myself as an old, fat man who's not taken care of your body after you wasted your good, strong, sexy years trying to make every woman love you.' And it hurts. But then the sun comes shining through and I still love him, even in this journey where I also hate him.
So...I am rambling and long winded and possibly make little sense but I'm trying to say... I don't know if its worth it but I value marriage as something not expected to be easy so it holds me longer than it might someone else and that maybe trying NOT to patrol him but let him show YOU what he is or isn't doing. And understand that we never really do know...with anyone...really hanging on to this idea can be at least somewhat liberating in regards to feeling like you need to patrol.
I'm no MC but for my husband, putting the reigns of his behavior in his own hands with the understanding that I wouldn't tolerate certain behaviors seems to have helped a lot. He can *do* whatever he wants...anything! But it doesn't mean I'll still be waiting for him when he's done. Consequences exist.
If none of that is helpful, please at least accept a cyber hug from a girl who hates hugging :)