My theory is that Jillian and her husband were in an open relationship, but then she fucked Moon and that completely destroyed his ego. She has an onlyfans where she rates dicks, there's no way their marriage was anything approaching normal.
When it comes to these types of people, putting in any kind of effort to understand their definitions or rationale for things is useless. They operate on a meta-physical baseline, several orders of magnitude removed from the general population.
They're the kind of people who will be 100IQ college graduates, while also being both mentally and functionally retarded.
These are the kind of people who determine the definition of words based on their current situation, their morals, and how they feel at the moment. The traditional definition of marriage is a monogamous relationship bound by a legal contract between 2 individuals, recognized by God and/or the state, with the key word being "monogamous," which can generally be boiled down to exclusivity for sexual and romantic acts between 2 partners. The definition of an open marriage can be a bit more vague, but the idea is that it's almost the same thing, but is non-monogamous.
The thing is, though, in the current day, there are people (Like Jillian and her cuck husband) who don't like the idea of restrictions they morally disagree with on how a woman expresses her sexuality. So in turn they decide that since they don't like some of the restrictions, but still "vibe" with the term monogamous, they'll just redefine the term in their head, and claim they are "monogamous" but it's their version of monogamy, the true and correct version of monogamy that has "flexible" or non-defined boundaries.
This is how you get people claiming they are in a happy monogamous relationship while they or their partner are essentially prostitutes and are basically in an open marriage.
Inevitably the lack of boundaries or defined acceptable behavior leads to them actually fucking someone, because funny enough when there are no defined acceptable/unacceptable terms aside from
1. we are in a "monogamous" relationship, and 2. Don't fuck somebody else, it's really easy to end up in a situation where someone has done basically everything but fuck somebody else, and at that point for people with this twisted methodology, the logical next step is obviously to fuck them because while there's a boundary to not do it, this circumstance is completely different and in their mind is the morally right thing to do. Then their partner looks like a fucking retard because, in their mind, they were monogamous, and that means this kind of thing shouldn't happen, even though to literally everyone else, it is evident that it would.