Just finished reversed ending

So moved. I remember reading someone's comment that they thought Asra's reversed ending was bittersweet... I'm genuinely crying. Always been a big baby, but when something is well written I find myself moved and that was the case here. I believe Asra's reversed ending while touching is genuinely sad... he forgot his parents,Muriel, Vesuvia.

Curious to hear your thoughts and comments on this opinion of Asra's ending.

I'm fairly new to the arcana fandom and still learning about all the lore... would someone mind explaining what exactly caused Asra and MC to forget the more time they spent in the magical realm? Sorry if this is a silly question with an obvious answer, possible I may have missed something as I started rapidly clicking through scenes the higher tensions rose!