Hello Jameshumber,
Sometimes you need rules, sometimes not. For example, you may need some rules right now, as you are just starting out. Like having training wheels on a bike. Later on, as poly gets easier, you may feel that you can relax some of those rules. Change some of them into guidelines perhaps. Everyone is different, so every relationship is unique. You will need to decide what (if any) rules work for you.
Regards,
Kevin T.