My exh did the housework too while we were both working, before children. There was a lot less to do back then. He wasn't great at cooking - but we were both young so it didn't surprise me. I had learned to cook better over the years and thought we would both continue to learn - why not, I thought. He also said all the right things; that women were equal, that he wanted to be a hands-on dad.
When our first child was born, at first he did things with her - but I was a SAHM, so expected to do more childcare. I was pregnant with our second child without going back to work in between: they are two years apart, so I had a little over a year during which I could have decided he was too shit a father to have a second child with - but it was a year during which our whole plan was for me to take on the majority of the childcare.
Over the years, my exh gradually did less and less, until by the time I was ready to go back to work, I was in charge of it all. And when I did start work again, by that point he saw me as the housewife and him as the earner. It was only then that it became really clear to me that things were not going to become more equal again.
His attitude never really changed after that. But before we had kids, I didn't know that was how it would end up. And when our dd was small, it still felt like a temporary situation. The shift was creeping; hard to recognise. It wasn't something either of us expected: I'm sure he did intend to be a hands-on parent. But like many of us, he was underestimating how much time and effort that requires.
I carried on learning to cook. He never learned any more: if anything he's regressed, as he can no longer be bothered to put any effort in at all (reading between the lines of what the kids report!). I don't think it's a coincidence that we both ended up following traditional role models. But when we were young, it didn't feel as if that was the only possible outcome.
I don't think it's useful to act as if these things are obvious, and we should know from the start that a man is going to be an equal partner or not - because if women think that, then (like me), they won't spot the gradual changes, over time, and won't realise that those changes are stoppable.