Another parallel I think of is how many people I know, where I know very little about their relationship
or their spouse. For example, my first cousin recently got married. I see him less than once a year and have not said anything more substantial than "hi" to him... well, ever, probably. Although I have a vague recollection of meeting his bride once a couple years ago, her face was totally unfamiliar to me in the wedding pictures I was looking at online.
I have absolutely no idea under what circumstances they met (maybe they were cheating on someone), how healthy their relationship
is (maybe one of them is abusive), what its chances for longevity are (maybe they're completely ill-matched), or how seriously they take it (maybe they are already cheating on each other). Yet, I easily assume that the answers to all these questions are good, and I have no plans to treat them differently from any other married couple just because I don't know for sure. For example, I will address next year's Christmas card to both of them, and if I was inviting my cousin to a family gathering I would also invite his wife.
Sometimes having more information is actually worse, because if you know nothing, you can assume everything is fine. In this case I would know the couple met and married for a TV show, which in concept makes me
at best. I think to be polite I would just need to set that aside as much as possible, and treat them as I would any other marrying/married couple. I didn't attend my cousin's wedding, but I did send a gift, so I would probably go that route in this case.