I’ve misread it 
Oh Elyn would marry the Old Ones never being able to see your best friends ever again , is such a tragic fate.Good friends are like family
Also yeah she’ll be rich so there’s one good thing.
Since it’d be too clear with the characters from our historical romance, I’ll go with the action fantasy WIP I’ve been cooking up for years:
Argenta: Hmm, never talking to my friends again or marrying the- HOLD UP MY SISTER IS LITERALLY DOING THAT NOW THAT’S WHAT THE STORY IS ALL ABOUT
Hafella: Not talking to my friends again? Nah, I’ll marry the- NO KAYA WE WILL NOT BE DOING THIS, FORGET IT.
Meanwhile one of the antagonists:
Hmm, I don’t have any real friends, so I’ll marry Hafella just for fun. So that I can tell her that this “Kaya” she speaks of is actually the evil portion of her own brain. Then she’ll be suffering and I will have fun!!
Ooh, this is a tough one. But I think Mancer would want to have nothing to do with Edwin whatsoever. He'd probably choose the third answer of destroying the whole universe. 
I'd say that counts as justifiable omnicide.
Got another one for you: Would your MC rather play truth or dare with a Cthulhu mythos Elder God, or never have I ever with an ancient malicious fae creature?
this, lol. Mora and Christopher are already going to be interacting with an ancient malicious fae creature, never have I ever would be the most chill thing they do with her lol
Truth or dare with Cthulhu does sound well deadly but also fun
But Elyn would have more entertainment with malicious fae
Neither Red nor Malice would want to marry each other (especially not with the extremely stetchy age gap), sooo I guess bye forever, Jin!
...Wait, that could be bad too. Uhhhh
Red: ...I feel like both of those options are just asking for trouble...?
Depends on who you define as the best friend. Qamar and Najm along with Rahat and Alya are probably the best friend in the purely platonic since and all of them would 100% bail on each other if they had to choose between staying together and not getting with Leopold. Qam and Najm would be bummed about it, but I reckon that Alya and Rahat, as much as they like each other as people, would take the random disappearance of their counterpart in stride, Rahat more so than Alya.
This is mostly due to the fact that working in the Tazdahir means that anyone you care about could die randomly at any time, Rahat grew up with that and is used to people appearing and disappearing in their life. How troubled they are about cutting ties with someone they care about directly correlates with how long they've lived in the Tazdahir, with Rahat being the least bothered and Qam being the most bothered.
The answer changes if the best friend is someone you love both platonically and romantically, i.e. Rahat X Qamar and Alya X Najm. Rahat still wouldn't marry Leopold, they'd almost never willingly endanger themself and being near Leo radically increases your chance of death. Najm wouldn't either, they hate Leo more than they love Alya. Qam might, one of the few reasons that they're still alive is their relationship with Rahat, and that would be compromised by being married to Leo, but not as much as them being completely cut out.
Alya would marry Leopold if it meant they could still be around Najm, they don't hate Leopold, they don't really care either way about him, they think that being under the thumb of someone like Leopold is inevitable and they even have a certain level of respect for him. Alya just thinks that they could run the corporate empire better than he can. Alya loves Najm enough to risk their own safety, but also thinks they're smart enough to bend Leo to their whims.
I'd like to clarify: I don't believe what Alya believes, but I think that Alya's beliefs are completely normal for their circumstances as someone who has spent their entire life being controlled by a system that they have been told is meritocratic, and has treated them like they're nothing. Anyway, this thought experiment is kinda moot, because Leopold thinks that prolonged contact with the poor will give him viruses, so would never marry into the lower class. Which he perceives as pretty much everyone, except maybe the Curator, who is his sister.
For all main characters in "Apparent Secrets" I'd say that literally no one wants to marry either antagonist. One is a malignant POS, and the other is only alive for the sake of revenge. I wouldn't wish that marriage on anyone. Even the antagonists wouldn't get along with each other. 
As for the "Of Lowlifes, Lutes, & Liars" crew, I could see Khazmine marrying the antagonist to get close enough to them to uncover their evil plot, but I doubt very much that it would ever get that far. Aranthus and Pavocinis are "marry for love" kinda guys, so they'd probably choose not to see their BFF again. The way things are going right now, that might be on the table in the future... 
I just thought about this with Victor from my story Fuego de Sombra (which I just finished writing the comic script for. Won’t get around to actually making for another 5 years lol)
This one is easy- The antagonist is his dad 
I think he would rather never interact with his nonexistent bff lol. He has no friends for basically the entire story, except for the very end when he becomes friends with his step-aunt. I think he would be okay with losing his step-aunt. Especially since the other option is horrible.
I’ve been cooking up ideas for a sequel though, and his choice would actually switch if he got this would you rather then. He’s a lot closer with his aunt by now, and the villain isn’t his dad I can actually see him getting along okay being married to this villain. Their dynamic would be so funny honestly- Not that he would willingly marry her, but if forced to he would be able to deal.
Noooooooo help this is making me want to marry him off to her aghhhhhh
That would be so stupid help I’m almost literally crying- She is 1 1/2 Victors tall 🥹
Little Owen Moriarty is a kiddie MC so skipped him
Evan Moriarty- 
"Sure, I'll marry the villain, no biggie they prolly fancy me anyway, keep the friends, fool around on the side. I'll be close enough to kill that villain on cue!" 
Xun-
"Nop not marrying no villain at all. Never interacting with my BFFS is a life I'm currently getting used to, I'm the super spreader of an outbreak after all, not by choice either... Plus I dunno...Raffa's being...difficult lately 
Raffa-
"Gee!.... Marry the villian!? That loser got 0 chance!
Tell the BFF (Xun) he can stay away, can't guarantee yet if I'd infect him like I did to those other civilians a few hours ago. Also, he's been so distracted figuring out how to babysit survivors, we could've long figured a way to kill that Godzilla Sized Shrimp!.... I'm forever better off doing this thing solo! 
@Leyelle don't worry, I think he just being a dramatic big wolf-ey 🤣 Have a feeling hed come around🤞He'd be hardest to convince to marry villian for sure lol
Alicia: Wait, who is the antagonist of this story? Is it my boyfriend's mom, my ex boyfriend, or me? If the antagonist is me I would marry and then divorce myself, because I'm definitely not about to stop interacting with my bestie...who is also my boyfriend.
27 days later
Would you rather ditch your best friend for one million dollars or have them ditch you for 1 million dollars?
Alicia: Wait, what kind of question is that? Obviously I wouldn't want either.
Me: but you have to pick one.
Alicia: I guess I'd have to choose him ditching me because I wouldn't want to cause him life long trauma.
Meanwhile Jinho and Andrew.
Jinho: I'd have to ditch him, because he's a perfect little angel, I wouldn't want to make him sacrifice his morals. I know he'd never get over it and he'd feel guilty for the rest of his life.
25 days later