The birth of our kids was also the tipping point in my marriage. As PPs have said, the combination of pressures - small children, lack of sleep, moving to a bigger house, higher outgoings, much more stressful job - resulted in DH’s mental health taking a nosedive. As a result of which he became ever more unreasonable, demanding, controlling, spiteful and generally cunty.
And I had stupidly given up my career a few years in, so I was effectively quite isolated and felt like it was my ‘job’ and duty to make everything ok for him, so increasingly the whole household revolved around his needs and no one else’s.
The whole shitshow was a bit of a boiled frog situation, tbh - over a 10 year period we slowly went from being happy and optimistic and effectively a pretty good team, to me being permanently anxious, unhappy and treading on eggs, and him being correspondingly more controlling and abusive (though never physically).
We’re still together (when he realsed I was about to leave him for good it shook him out of his denial) but it’s taken years of work to repair the damage and it’ll never be the same as it was when we were young. There’s part of me that’ll always be a little bit broken, I think, partly from the shame of it (I appear to be a stridently confident and articulate person; no one in a million years would guess that was the true dynamic of our relationship behind closed doors), and partly from grief at those lost years when I was in the thick of it.
The other thing to say is that my DH, though he has behaved unforgivably in some ways, is a good person, who battles daily with his mental health and demons from his awful childhood. People are complicated. Relationships are difficult.
So in answer to your question, OP, no, you definitely can’t always see it coming, and anyone who tries to blame or shame you can get to fuck.