I also believe Simba abolished the law, out of his love for Nala. Who I am positive that he proposed to rather than saying,
"Nala we were betrothed as cubs, so you are required to be my Queen."
I also believe if the betrothal law
were in effect, it would be a moot point. Because I'm sure that by Simba's standards no lion in existence is worthy of his little girl
.