
It really bothers me that Chika is just going to marry a girl he doesn't know. It feels like the author just threw that girl in so that Chika could be "paired up" and Hotaka and Masato's love story could begin.

Technically he does know her in a sense, because they went to school together... but yeah, I feel you. They don't know each other in any meaningful, relationship-building way. That woman doesn't truly know Chika as a person at all, she must have just been 'in love' with the idea of him since high school.
I really wonder if the manga trope of omiai/arranged marriages really still happens in Japan, even in old families with family businesses to succeed. Because seriously, Chika's situation is a way worse reason to marry someone than Masato and his ex-wife marrying because she got pregnant. (I like to think theirs was a case of an unnoticed split in the condom... because honestly, contraception is not freakin' neurosurgery. It's not hard to figure out.) And Chika was planning on this happening eventually, since the very beginning! He reminds me of Tachibana-san from Kasa No Shita, Futari.
Wait did he fake the memory loss? I read it as Someya regained his memories and left Uno because he felt guilty for lying in the past and forgetting about the trouble he'd brought onto Uno.
I read it as that too, maybe when he stared at the moon all the things that he tried to forget submerged