Probably a mixture of all scenarios. Our decision to split was mutual but even after deciding, we were still faffing around and the eventual push was from my side.
A lot of the bahaviours described were part of my decision but it was the underlying issues that made me notice them more if that makes sense? In an otherwise happy and loving relationship where I felt loved and valued, banging the toilet seat, leaving his stuff in the sink etc would have been minor niggles associated with living with someone. In that absence of love and care, they become weapons designed to make your life more miserable.
I think you notice and rejoice in the absence of controlling behaviour more when it's not there and realise that things were worse than you maybe felt at the time.
Your poor mum probably felt trapped to stay and now feels it's too late, or maybe there's more love there than is obvious to you?
To be honest, I've always looked after and supported myself and my family and never really asked for much but I won't be woken in the middle of the night and accussed of things. Or to feel punished or inadequate because I was sexually abused as a child.
Was I a perfect wife? Definitely not. Was I ever malicious or uncaring? Also no.
That's probably a bit serious for this thread, but also to add that on a day to day basis we got on reasonably well and still do to an extent. He's started to make a little more effort with adult DSs and has offered me money (I don't need it and didn't take it) and has also offered to drive us all to DS2s graduation.
I think that as he's approaching retirement and nearly a year into living on his own, it's starting to sink in.