As someone who is not entirely monogamous, I can see both the upsides and pitfalls of this. I only live with one person and the finances, family, etc. are only shared between us. My other partner is considered a part of our extended family but he doesn’t have the same decision making privileges as we, the co-habiting partners have. And, when done right, this kind of relationship encourages good communication, getting to know yourself and your needs, management of ownership/co-dependant tendencies, etc. To really make it work requires a different mindset than is mostly in play in most people’s lives today. I applaud you for exploring it as a topic!