You shouldn't!

My theory as why Kopa is missing in SP:
Kopa fell in love with Asante
He renounced his right to be king to go live with her
I'm sure Nala and Simba were nice to her and all,
but for the Prideland animals, a hyena in charge would be history repeating itself.
Also, they wouldn't be able to provide the kingdom with an heir

And not a Vitani to be found.

Kopa and Asante c TLK