Breaking up is hard to do when the couple has children. Simply put, the children have been used to living with both of their parents, and when their parents separate or divorce, the children know that they will never again share a home seven days a week with both parents. Addressing that difficulty is a key issue in family law.
The parents, if they put their children above any need to "win" and make the other parent "lose", can do a lot to help their children after a separation or divorce by committing themselves to successful co-parenting. One key to doing so is understanding that each parent is going to take care of the children in a different way.
After all, each parent is an individual with their own individual personality, perspectives, values and approaches. It is OK for each parent to take care of the children in a different way and pretending that they have to do everything the same way would be a source of interminable frustration.
That said, both parents do need to determine some key things that will be consistent for the children across households. For example, they should agree to enforce the same bedtimes, so the children have consistent sleeping schedules in both households. Both parents should also be in agreement about the dietary standards that they will enforce, like avoiding candy or caffeine. Having the same rules in both households about such basic things gives the children stability and prevents them from playing the parents against each other.
Family law doesn't exist in isolation, of course. Parents looking to chart a healthy path for their children after separation or divorce can reach out to lawyers and counselors to help put together the arrangements that will work best for their families.