User blog comment:Genista882/Mitsuru and Kokoro 2/@comment-26567684-20190507210542/@comment-26567684-20190508175604

Goro said they were implanted with fake memories in episode 19. They were completely left devoid of memories of each other and the assumption is that their fake memories were of them remaining paired up with Ikuno and Futoshi. Their fake memories may also be moments with their previous partners rather than each other, as APE wanted to get rid of all MitsuKoko’s memories and feelings.

There is an old superstition in Japan that although the mind forgets, the body doesn’t. This reflects how MitsuKoko felt pain whenever they said each other’s names. It’s their bodies way of trying to make the mind remember.

Remembering one thing and being told something else you don’t remember contributed to their initial coldness towards each other, along with they were scheduled to participate in the supposedly final battle with the Klaxosaurs, which made them focus more on their futures than anything else. The pain they felt caused them to question what had really happened between them and what it could mean for their future but their feelings were different. Mitsuru was confused but felt a need to be there for her and wanted to talk to her, whereas Kokoro was scared and pushed him further away. But once APE collapsed and they learned they were having a baby, this opened the door for them to reflect their relationship and future.

I’m not saying Ai is the ‘glue’ that keeps them together; she brought joy and peace into their lives, and allowed them to fall in love again as they raised her together.