Not hating, but I am honestly curious why you see potential in rivamika as a ship that would work, because in the anime/manga, most of the time I feel like everything Mikasa does is for Eren (especially in the anime, most of her lines are seriously just some variation of 'Eren'), just as how everything Levi does is for Erwin. And their interactions actually mostly revolve around saving Eren. I can't see them stop thinking of Eren/Erwn long enough to even notice each other tbh.
There’s actually a lot of reasons why, actually. Please note that I’m going to discuss why I think rivamika has potential, but I’m not trying to prove they have any romantic potential because I don’t personally think they do due to the theme and circumstances of the canon story (AUs/UAs are another story). However, there’s quite a lot of evidence that supports the ship. Maybe it won’t be enough to convince you, but it was enough for me and many other rivamika shippers.
Honestly, this fandom (and many others) have paired characters together with much, much less potential so I don’t know why so many people think rivamika doesn’t meet “shipping requirements.” I mean, part of the fun of shipping is being creative and match-making characters you personally think would make a cute couple. Hell, I even ship characters that barely/never interacted before because I think their personalities match up well and I like to imagine the possibilities. This is why I’ll never understand why fans these days have to explain themselves and provide proof, but meh. I got nothing better to do lol.
I also want to note that I was fascinated by Mikasa and Levi’s relationship/parallels before I started to ship them–that was more of an aftereffect and a way to express my love for them. In other words, I’m capable of being unbiased while discussing their relationship :)