The reality is that every relationship has its own dynamic (it is probably the only aspect of existence that cannot be reduced to math) and as no two are alike then generalist, judgemental comments are pointless.
My other half and I separated 15 months ago and so co-habit in order to co-parent our only child (still in primary and so far has not completely clocked we are split). The rough deal we have made is to struggle through for a couple of years, until he is 8 when we think he could better handle the split (he had a serious medical issue when he was 4-5 and from which he is still adjusting and so do not think it would be good to add extra trauma of his only family dividing).
The fact is that after 15 years she said no more sex whatsoever, it had been a
steady decline from about year 5/ over the last decade. Then two weeks after the prohibition on sex told me she wanted me to move into the 'back bedroom'. About three months later she confirmed that she wanted a permanent split. It was not a perfect relationship but to this day I do not know why she wanted to separate - she is not very communicative, and despite saying she would have counselling never agrees to go.
I make about double what she does - she refuses to get a better paying job cause she is 'committed' to her work ,) And I have worked to point of exhaustion to get us into the house we have (the 60% deposit was all me), pay for the 3x a year flights to her family in Europe etc. She did try to discuss our inability to have more kids (which I wanted as much if not more than her) but I was so broken about it and not being able to afford any more IVF, that I kept putting it off - I did apologise for that but she did not accept my apology. Coupled with fact I had a traumatic childhood that my parents ignored, and it recently became an issue, I have been struggling to keep my head above water and not be miserable in front of my child.
She is not British and wants to move back to Europe with our child, which I opposed. I know she is interested in having another relationship as soon as (she is more sexually liberal than me and during our relationship once asked to go with someone else, which I think broke my heart and my inability to ever heal that probably doomed our relationship from then).
Anyway, all I want now is to get back my deposit and get on. I accept that this is all from my perspective and I am sure she has hers, but as an example, we have both become older and inevitably less attractive, but I am constantly told I am overweight and I so now run a few days a week and completed a marathon a month ago. Whereas she is much larger but if I were to suggest anything then it would be sexist, which is a real double standard.
The sad thing is that I fantasies about her almost every night when I am alone in bed, look at photos of our small family after we had our child and cry to sleep. But I am not going to let her break me cause then I will have nothing, and my son will not have a father. Since I have known her I can count on one hand the number of times she apologised for anything, whereas I am constantly at fault, even for something to which I have no connection. I am desperate also to get into counselling, if for no other reason than to confirm that it is her who wanted to separate, otherwise I feel like I am being blamed for being rejected, which is rubbish.
She constantly says I do not do enough – I make most of the money, bought and repair our old house, spend all my free time with our child, do over half the housework, and deal with her family (who are not helpful), and as I have told her, I cannot do more and am at my limit.