I don't think the EMA bond was ever strong, if anything they were holding each other back. Due to Mikasa attachment to Eren, she was moving further away from becoming her own person. Which I think was the entire point of the table scene, he wanted Mikasa to move on from him, think about herself because her life is more than she's trying to protect him.

He was mean, rude and whatever bad word you can throw at her, he made her doubt her whole existence which is the worst thing you can do to someone but that's originally made Mikasa reflect on herself.

Erehisu already had their development, she was not in the way or needed to die for it. Honestly, her entire character was about moving on from Eren, even Isyama said how it sucks if her character only revolves around Eren and that's why I think in that crappy ending she married to another man.

Honestly, after the development, I think Mikasa will choose Armin side since it was morally correct and much more lives were at stake.

I don't think Historia and Eren is only about understanding each other, it was more about acknowledging and accepting their selfish side or morally corrupt side.

From chapter 123 we know Mikasa actually had the idea that Eren was always like that but she ignored that cause she couldn't accept that Eren is not her white knight or the kind person she thinks he is. In reality, he's different who would destroy comes in his way.

I think what we are missing is middle context aka Mikasa character development which would have to reflect why she would take Armin side. Also, the entire rumbling arc was wasted which also could have used for this said development.