Bali and Balinese are very open. I remember traveling with my wife in Sumatra before we were married and weren't allowed to stay at a hotel. It was a hotel recommended in Lonely Planet. It only happened one time. I don't agree with Sacha about the Four Seasons. If this was law, wouldn't they feel more obliged to follow the laws of the country, than a budget hotel?
Unless there were some kinds of strict fines or something, no hotel at least in Bali, is going to follow this law. As others have written these regulations already exist to a certain degree. I thought adultery was already a crime.
This was posted in 2016:
https://balipod.com/forum/threads/the-family-love-alliance-is-coming-to-get-you.11705/
From 2013:
https://balipod.com/forum/threads/unmarried-couples-caught-having-sex-could-face-jail-time.8925/
Australian woman arrested for adultery in Bali (2011):
https://balipod.com/forum/threads/australian-and-balinese-arrested-for-adultery.6589/
I am 99% sure this would never be enforced for tourists. If a foreigner lives with a local then they could be asked to get married. I have heard of foreigners being pressured to marry by family/village.
Like most people, I hate governments interfering in our lives. The main issue I had with this, was the way it has been blown up by the Australian media.