Sure, it's official. Usually, when a manga is associated with a well-known game like Elden Ring, it goes through a proper licensing process to ensure quality and authenticity.
Not that I know of. Usually, you can find out by following official announcements from the publishers or checking dedicated manga forums for the latest updates.
It's usually the emotional depth and the romantic elements. The story might explore the meaning and significance of the wedding ring, making it really touching.