They don’t conflict. He acted badly and drove her away. She ended the relationship, but it wasn’t like he was blameless. On the contrary, he’s probably the primary reason they broke up. But she’s the one that ended it.
I don’t think, before the first verse, that he ever expected them to get back together. But the future was undecided. But now that she found someone, it is finished for sure. No going back.
I was never sure if he cheated on her. One can interpret
“What are these voices outside love’s open door
Make us throw off our contentment
And beg for something more?”
To mean he strayed, but it could also just be an existential need. He didn’t want a different woman, just a different…something. A yearning undefined.
Of course, “And how I lost me and you lost you” could mean she cheated. But people cheated all the time, then. Now. Forever. Cheating alone isn’t often sufficiency to end a relationship. (I mean, it is for me. But that’s me.) So they got lost in the emptiness of modern life.
All he knows is, the relationship is gone, but he has the maturity now to believe he (and her, but not together) can still be salvaged. There’s hope for the both of them, if they can just let go of the past.
Same as Boys of Summer. The video really made it apparent - the singer keeps reliving the few short, happy memories of the past, these brief moments in time, like old home movies, and can’t let go. There’s nothing else BUT those few moments of happiness, but that’s all he can see, even decades later.
Don’t look back - you can never look back.