Okay idk why but why do i feel the reason he doesn’t like his eldest daughter is because...

Okay idk why but why do i feel the reason he doesn’t like his eldest daughter is because of her mother. Stories like this, the mother usually push themselves to the Emperor for their kids to have better lives or to be next in line. I’m not saying he’s not going to be irresponsible since is his child but he’ll make his second kid is the heir no matter what so the child’s family doesn’t pop up unexpected to get control of the crown