It was a fairly short bl manga. The main character goes to confess his love because he believes the world is ending[m] (or something along those lines) and his childhood crush is know a shut off author. They are both adults. I think they live together for awhile and at the end the love interest accepts and returns (?) the feelings. I read this like a year ago but I don't think it was a super recent story.

Sorry if I did this post wrong, its my first time posting here.

Is it If the World Was Ending Tomorrow?or maybe Ringo ni Hachimitsu

Thank you so much 🙂 it was Ringo ni Hachimitsu !