so given that - I'd say it would be perfectly acceptable for it to work the other way and a step father not particularly love his children either
Big difference is when a step parent lives with a child. It’s is very hard to build and maintain a parenting relationship from scratch when you see a child a couple of days a fortnight. If you live with the child, are involved in their daily routine, it’s a different relationship.
My brother used to take his kids to school every day, do bath time, read them a story every night. Take them to their swimming clubs, karate classes, walk the dog with them.
Now their step dad does all that because he lives there. They don’t remember their dad doing that, he sees them a lot and they have a good relationship, but it’s not the same as living with a parent, and their relationship has definitely suffered.
A step parent living with children that relationship can grow and boundaries can be set. A step parent who sees the kids once a week not so much, especially if that step parent is female and if they do take more of a parenting role often gets slammed for not being their mother etc…