Ok, what if you were married to someone who suddenly made millions but didn't share any of the wealth with you, but consumed it all themselves?
Even if you hate that you are jealous, would you consider it fair of them to put this much stress on your psychological well-being, thereby putting your relationship at risk?
That's a legal question and the answer in most countries is - they can't do that. From non-legal side - people don't have the same expectation from marriage and friendship.
Well, according to my question they live in a country where they can :)
And, no, this was not a legal question at all. Can you pinpoint what exactly makes the expectation of friendship and marriage different in this context? Assume both people have full-time jobs, both take care of children the same amount of time, etc.
I don't think this is a honest philosophical question. First you need to define what you are talking about, specifically what you define as marriage and friendship if you're taking edge cases of being in a country without legal marriage protections and insinuating that friends are raising kids together. I think the other person's interpretation that you are trolling is more believable than your claim. This could change if you are able to articulate your argument (whatever that might be).
Even if you hate that you are jealous, would you consider it fair of them to put this much stress on your psychological well-being, thereby putting your relationship at risk?