I think they're just fine. They Любовь each other very much. I don't think they have any problems. Simba maybe overly protective of Kiara while Nala isn't. But Simba is a very caring and he doesn't want his daughter to get hurt. Nala tells Simba that she'll be fine. Simba and Nala Любовь each other and nothing will change it.
I say Simba and Nala ' s marriage is going pretty fine. Simba may be a little over protective over Kiara. Nala isn't. But that is just normal Dad/Husband and Mom/Wife stuff.