You can read this at LINE Webtoon or at Tapas. It's free to read since I've read this yest...

I tried finding it online but have no luck, by any chance is it under a different name?

First result when I googled "Line web toon fated mates" was this: https://www.webtoons.com/en/challenge/fated-mates-omegaverse-/list?title_no=162895