This is how I view it, generally speaking.
The marriage we had pre-A, is dead and gone. I ended it the day I broke my vows and betrayed my wife. It cannot get "better" or "work" because it does not exist. We aren't divorced, so we may be "still married" on paper, but the marriage itself is over. I think it can be difficult for people to accept this point of view on an emotional level. We want the marriage we thought we had when we fell in love and rushed off to live our lives together.
Any relationship, marriage or otherwise, that we have moving forward, is something new we are building together. And this time around, we have a much clearer picture of who we both are, what we want in a relationship (and what we don't).
After many years of therapy, struggle and hard work, my emotional and mental self is much healthier. So much of who I was and how I lived my life was built on shame and fear and trauma. I did not love myself and had no idea how to love others, no idea what a healthy relationship even is, because it was never modeled for me. My wife also has worked through IC on her own, and MC with me, and she too has learned many things about herself, dealt with some old emotional issues, and has grown a lot in terms of vulnerability and her ability to "detach" from things that shouldn't affect her life.
So, can two people, who have worked hard and grown as individuals, and also worked hard and have grown as a couple, build something new together that is better than what they had before, using what they've learned, and having made conscious decisions about what they relationship looks like?
Look, don't get me wrong. I'm not saying that any of this ever goes away or becomes okay. Trauma is a scar that never goes away, you just learn to work with it.
And if my wife changed her mind one day and decided to divorce me, it would STILL be a better working relationship than we had before, because we're different people now. We can have the hard talks and not avoid conflict. The trauma that kept us from living our best, authentic lives has been addressed, and we have new tools for both joy and conflict. We know each other, and ourselves, so much better now than we ever had before in our lives. Life isn't always rosy, but we've seen improved relationships with family, friends and work, because who we are inside has changed fundamentally.
I dunno. Think of it as a kitchen remodel. You can never get back the kitchen you had, and that's okay, because even though you may have fond memories of time spent in that kitchen, it wasn't really ever working the way you wanted it to, so you destroyed it. It is gone. But you CAN build a new kitchen, having learned lessons from the old kitchen, and build it so that it is much more functional and has what you needed all along. The process of remodeling is endless, expensive and messy, so you have to decide if you are willing to put in that time, money and effort when just leaving and buying a new house is also an option. But with a new house, you have to take an already established kitchen, it could suck as much as the old one. At least with the rebuild, you know where you stand. And if it still sucks, moving is still an option. But putting that much time and effort into something you are building changes you, in a good way.
As the song says, "Today is where your book begins, the rest is still unwritten".