Would you be saying the same thing if the MC was the ML's parent or sibling? I'm not saying it's the same dynamic, but if you have been together for over seven years I think you have the responsibility to take of your fiance who just had a traumatic head injury.
On top of that I didn't say that he had to be forever devoted to this man who is treating him like shit, just that the MC could have waited a little longer and helped the ML ease back into his life. And maybe along the way the ML could have understood or atleast stopped the undeserved hate.
Honestly it's weird how he didn't even try to trigger the ML's memories, I'm not sure it would have worked, but wouldn't you be desperate enough to try? If nothing else the photos or videos could have been undeniable proof that they were together.
I won't blame the MC for protecting his peace but the bare minimum would have been to wait until they got home. Bare minimum.
All I can say is that he was under pressure to do that. I can elaborate more of you want l, but that'd be spoilers. But, yeah, the breakup is what makes Yoon act so hostile toward him. Like, even without memories, he still feels like he lost something important and abandoned as shown in the current chapter. So when he heard Seojeong participated in a dating show, he felt hurt and betrayed, thinking Seojeong live well while he was depressed. To sum it up, both of them think the other live happy and unaffected after the breakup while hiding their own pain.

can i be honest? It's kinda shitty of the mc to leave the ml so soon after he woke up, i mean my dude is still in his hospital gown. Like, i get that he's a piece of shit rn but i feel like you owe it to the person he was. If you dated for 7 years then the least you could do is give him some time to adjust, I'm not saying that the mc have to put up with his bullshit, but it really is an ass move.
Not that the ml is some kind of saint, I'm just sayinng he had a point when he said the mc abandoned him