Answer:
As an author myself, and a reader i'm answering based on what id love to read so i'm sorry if it isn't good enough, to answer your first question
1. they are immortal because the character wished from a falling star, thinking that it wouldn't happen.
2. their families slowly died and he or she have to switch identities so no one would realize that he or she is immortal. they become depressed to the point where they try to stay up to see another falling star to make a wish again that they are not immortal but he or she never saw one.
to make it a happy ending the character saw a falling star and wished to follow their loved one in the afterlife.
Explanation:
