Manga about two girls who get reincarnated to another world; one marries a prince while the other marries a blue-haired knight

Question

All I remember is that two girls reincarnate to another world together. One was supposed to get reincarnated while the other was supposed to die, but rock spirits really liked her, so they begged the god to reincarnate her as well. The one who is supposed to be reincarnated gets married to a prince, while the other one gets married to a blue-haired knight.

The story is in black and white and reads from right to left. On the cover of the manga, there is a black haired girl and a blue-haired man who are the main characters of the manga. I think the girl was wearing a pink dress on the cover.

Answer 1

This is That Time When I Was a Side Character in a Magical Journey.

From Baka-Updates:

Transported to a kingdom in another world with her friend, Michiru finds herself in the care of the handsome knight, Cainlotte. His demeanor is as cold as ice... But it turns out he's embarrassingly sweet to the point of being overprotective! Will there be a limit to her big-brotherly knight's fawning!? Find out in the long-awaited comicalization of this romantic comedy about an everyday girl who was just in the wrong place at the right time!

Michiru and her friend, Maki, are transported from Japan to the world of Estelia by a magic stone Maki bought in a shop. In Estelia, Maki is courted by a prince while Michiru is placed in the care of a blue-haired knight named Cainlotte. Michiru is subsequently told that she was fated to die in a car accident the day she was transported to Estelia, but the spirits of the stones in Japan asked the magic stone to save her.

The pages in the manga read from right to left, and the cover shows Michiru wearing a pink dress and standing in front of Cainlotte.