Do you think that Simba and Nala would have fell in love if they had grown up with each other? You know the whole betrothed thing.

Yes

yes,, its nice

Well, they fell in love even when Simba had disappeared for several years. So I'm sure it would have definitely happened if he hadn't disappeared.

Definitely. They were best friends so somewhere down the line, that strong friendship would have turned into strong love. They have a strong love anyways because when Nala realized Simba was alive, it really made her grateful and happy.