are supposed to mean the government does not interfere with your personal life, so long as you do not interfere in the lives of others.

Polygamy between consenting adults is not an interference in anyone else's life. Yet, it is banned in the west.

Furthermore, I had many liberal friends in America who believe that polygamy should be banned, unless it is between homosexuals (in which case it should be allowed because of personal freedom).

So there are some contradictions here. At least, if you are going to impose your morals on others in western societies, you need not continue lecturing others against imposing theirs in their own societies.