Ducks which force themselves on a female duck are more likely to be undesirable to begin with. The ability to filter out the weaker genes, and choose a "better" mate would lead to better offspring survival. Particularly if the female is already eaten limited by egg production rates.
The opposite has occurred in a particular Beatle (who's name I have forgotten). They have a perfectly functioning reproductive system. However, the male ignores it and stabs them through the side.
It turns out, in related beatles, when a female is mortally wounded, they dump out eggs as fast as they can, before dying. This causes a selection pressure which wiped out normal reproduction.
Oh I know to look after myself. You can't fill a cup from an empty pot. My partner sometimes forgets that though.
One plus side of being a parent. I now understand that, even though I was a little selfish shit at times, he loved me and so took the burden happily.
My minion can be demanding too, but it just makes me happy that I can make their world as good as possible. The point they understand the burden they cause, is the point they also give up childhood. I aim to put that off as long as possible. I will keep their sky blue and full of eternal sunshine for as long as I can.
And to clarify, I'm not coddling them. By the time they need to face the world, I'll hopefully have them trained to the point the world will fear their coming!