Mates: α/β/Ω [manga]

Truth be told I did not finish this, I only manage to read up until chapter 11. It's not that it isn't good, it's way too heart breaking and reading ABO AUs I have a set of mind, wondering whether they're fated pairs, I know the "rareness" of it, still. That's why this manga broke my heart. It's complicated and messed up thinking that if he hadn't done THAT when they were in middle school the situation would've been different.