How can you tell an unregistered polygamous marriage from simple cheating?

The Star has an article about a family that was broken up when the wife ran off and eloped with another man even though they were still married. The Star makes this out to be a problem with Canada's polygamy laws, but I think really this is just a case of cheating. It's sad, of course. Emotionally devastating, in fact, and broke up a family. But if they didn't attempt to legally register a marriage, it isn't polygamy under the law. It's on the exact same legal footing as cheating. And, like it or not, cheating isn't illegal.

But the laws themselves do have their problems.

According to the Criminal Code, those who enter into a polygamous marriage, polygamous conjugal union, or officiate at a polygamous union can be charged with a criminal offence and face up to five years in prison. Even if the marriage is not registered, it is still considered a crime according to the law.

How would the law enforce that? By definition, a marriage that is not legally registered has no legal weight, so in the eyes of the law this is exactly the same as simply cheating on your spouse.

Here's what the Criminal Code says: (copy-pasted from The Star, not from the Criminal Code itself because I'm lazy)

(1) Everyone who:

(a) practises or enters into or in any manner agrees or consents to practise or enter into
(i) any form of polygamy, or
(ii) any kind of conjugal union with more than one person at the same time, whether or not it is by law recognized as a binding form of marriage, or

(b) celebrates, assists or is a party to a rite, ceremony, contract or consent that purports to sanction a relationship mentioned in subparagraph (a)(i) or (ii),

is guilty of an indictable offence and liable to imprisonment for a term not exceeding five years.

Look at the part I've bolded. Doesn't that make a shared polyamorous household illegal? Like if you want to live in a great big poly orgy house, where everyone has sex with everyone else with everyone's knowledge and consent, that would be illegal under that paragraph, no? That doesn't seem right. If you want to move into a sharehouse and have sex with everyone there, that's not the law's business. It's the law's business if it decides not to grant all of you the full rights and privileges of marriage, but it can't stop you from all fucking each other.

But if you keep all your polygamous spouses in separate houses like Bill Hendrickson does, then you're fine, because a conjugal union other than legally-binding marriage has to be in the same household. There's no way legally to have a common-law spouse who lives in a different household, so if your polygamous spouse lives in at a different address and you haven't attempted a legally-binding marriage, there's nothing the law can do.

I think the problem is that what marriage laws are capable of doing is governing who can and can't get the legal rights and responsibilities of marriage, but they aren't capable of stopping people from sleeping together or building households together.

So, unless the law is going to make cheating illegal (somehow I don't think the general public would stand for that), I'm thinking maybe the solution is to legalize fully consensual, non-coerced polygamy. The people being profiled in these articles seem to take marriage seriously because they are acting like they're married to their new partners rather than just running off and cheating. So make it so that everyone has to actively marry everyone else, like say wedding vows to everyone else. So if the Big Love family did this, Bill and Barbara would say wedding vows to each other, then Bill and Nikki would say vows to each other, then Barbara and Nikki would say vows to each other, then Bill and Margene, then Barbara and Margene, then Nikki and Margene. And they'd all sign the marriage certificate, and if any one person did not consent to any new union, that union could not happen. This practice would address the situation in the article and the situation they wrote about last week where this lady's husband married a second wife without informing her. They could throw in some kind of anti-coercion clause to address those cults and make sure everyone involved is fully informed and consensual. Polygamists clearly feel that they don't need to get a legally registered marriage because they feel polygamy is part of their religion and the law doesn't respect their religion. So if the law just calls their bluff and legalizes polygamy with the perfectly reasonable conditions of full knowledge and consent by everyone involved, then they will have to abide by these conditions since they do seem to value marriage.

I'm congenitally monogamous so I'm not about to actively lobby for this, but I fully expect it to become legal at some point within my lifetime. And I fully expect the last and loudest protesters to be employers and insurance companies who have to provide benefits to people's spouses.