I was thinking about the fact that we don't see any male lion in the pride, besides Mufasa and Scar (and Simba), in the first movie and, on reflection, I realized that The Lion Guard probably explain their absence.
Thanks to the show, in fact, we know that there were four male lions in Scar's guard, and that Nala's father lived in the Pridelands at least since he was a cub.
My theory is that when Mufasa became king, the only males in the pride (in addition to him) were Scar, his guard and Nala's father. All the others, for example the members of the guard that saved Nala's father when he fell from a tree, were already dead, probably of old age.
When the members of Scar's guard refused to side with him against Mufasa, Scar killed them, and Nala's father, shortly after having conceived his daughter, died somehow (we know from the musical that Sarafina ate Banzai's father, so maybe Banzai's mother killed Sarafina's mate with the help of other hyenas as a revenge), and Mufasa and Scar became the only males in the pride.
What do you think?