Some abusive men like strong and confident women who call out behaviour they are not happy with at the start of a relationship. They appear to resolve any issues and so the relationship continues with what is assumed to be greater understanding of boundaries and expectations.
They play the part of a good partner with whom it is OK to share experiences with that might make you temporarily dependent or vulnerable.
Then bam you become pregnant, a new mother (even when planned), or random, bereaved, ill etc and it all crumbles overnight. In addition to the primary 'trauma' or experience you are also dealing with a DH who seems to have had a personality transplant over night. This really fucks with your head.
DH went from excitedly awaiting birth to unable to even lift 5lb baby because of mysterious back injury even though I'd had C-section and insisting that I did everything - he couldn't possibly take care of me or change nappies or even bring baby to me to breastfeed because he was in so much pain and I was evil for not putting him first. He was jealous of the baby breastfeeding ... let's leave it there, I will vomit if I elaborate.
They vacillate between anger and wanting to punish you and love bombing. Eventually it is just anger and desire to punish and you are a shadow of your former self.
It is only when you deal with the primary experience/trauma and with hindsight that you can piece together the side shit show and think maybe it was a red flag that they pretended to praise you and appreciate that you stood up for yourself and had such strong boundaries (unlike ex girlfriends or their mother). Really they were biding their time. Waiting for inevitable vulnerability.
But then maybe by then your temporary dependence and vulnerability has become the norm and you find yourself stuck in a relationship that seems to randomly switch from tolerable to abusive and you can't make it OK or escape without the help of woman's aid.