Please hide WN/LN/manga spoilers.
MAL entry, Anilist. The zeroth episode is a spin-off-ish, focusing on Sylphy after the Calamity meeting with Ariel, becoming “silent Fitz”, and struggling with her new situation; as well as the power struggles between Ariel and her brother I-always-forget-his-name for the Asuran throne.
The glasses are like Altair said, to make sex id harder.
The anime doesn’t mention address it, but the white hair is due to mana exhaustion. Basically she force consumed so much mana, trying to cushion herself against the fall, that it took a toll on her body.
The anime didn’t convey well enough that she was constantly using magic to help try and slow down her fall. As a result, a lot of people are missing the connection of the hair color change with the (over)use of magic.
MT LN Minor Spoilers
Don’t forget the glasses are a magic item which I’m sure will be revealed later in the show.