There are laws against killing because you don’t have the right to deprive another sentient being of their right to live and potentially contribute something to society as a whole (even if that contribution is merely to serve as a bad example.)

Again, laws are not moral or immoral, that’s not why we have laws. Cheating on your significant other is immoral, it’s not illegal. There are a whole host of things people consider to be immoral based on their own upbringing or religion that are not illegal.

Attempting to legislate morality is a fast way to failure. See the 18th and 21st amendments to the Constitution.