This is more of theoretical one than a personal one. English is not my first language so I am sorry if my post contains errors.
I've noticed on here that it is generally accepted that if someone enters into a relationship with someone who already has children that they are expected to treat those children as their own which includes paying for things and making sacrifices that are best for the children (some emotional, some financial). However when the parent has an asset like a property the feeling is that parents should not share with a new partner and that these should be saved for the children, even if this means their partner has no security.
I feel like these two views are contradictory. I think that if you expect someone to contribute to your child's upbringing as your partner then you should expect to support them and share security with them. If finances and assets are seperate then the cost of children should also be seperate and borne by the parent.
If the person who does not have children is less financially secure then unless the parent is willing to give them some security then they should not pay towards the children and instead should save money for their own future.
What are people's views on this?