Hot take, when it comes to Haikyuu Soulmates AUs Hinata and Kageyama should always be soulmates because thats the way god (Furudate) intended. No, I don't care if they're dating other people, in that case they're platonic soulmates.
Also, I need a Soulmate AU where platonic soulmates aren't the norm but they are not unusual either, and whenever Hinata makes introductions he keeps going on and on listing everyones soulmates and whoever they're dating (like "this is my soulmate Kageyama, and my boyfriend Kenma. This is Kenma's soulmate Kuroo, and his boyfriend Tsukishima. And that's Tsukishima's soulmate Yamaguchi..") until he gets distracted with something else and leaves whoever he was talking to confused and unable to remember anybody's name.
Bonus, Bokuto is always super excited to introduce Akaashi as his soulmate and his boyfriend.