You do not need to. You are under no obligation to do anything that makes you uncomfortable. [She was not the one, after all, who had sent someone a love letter.]

It can be. Sometimes it's obvious and other times you'd never know how someone feels about you until they give voice to it. Perhaps it would be better if people were more direct but it's hard to open yourself up in that way. Most people don't like to make themselves so vulnerable.

[Emotions is hard even for people who's emotions function normaly.]

It is... a vulnerable position you place yourself in when you love someone. That can be frightening to people.