Bonjour !
In my opinion , parents must be strict. Their role is to teach the limits you shouldn't get over. Children when they grow up need to know what a "no" means. It helps them to get structures. It doesn't mean that parents can't be cool as well. But not cool as friends. They always have to keep in mind they are the adults and are to be respected. Which I think mustn't be easy every day .
Chidren are always going to try to get over those limits, see as far they can go. Parents sometimes stop fighting because they are tired, or just don't trust themselves anymore. When they feel it's going to go that far, they should talk to their children, as if they were talking to adults and explain what's going on. That every one is going to suffer and it's time to make a rest. think together about new rules based on trust. If it's not respected, they 'll have to stop being cool and be strict again.
It looks a bit like a cat and mouse game !
bonne soirée
