In the manga, Tanjiro and Kanao don't end up getting married. The story focuses more on their battles and character development rather than romantic pairings.
Inosuke survives throughout the manga. The story doesn't have his death as part of the plot. His character remains active and plays a significant role until the end.
I would recommend 'Douma's Secret Admirer'. In this fanfiction, the reader is a shy character who secretly admires Douma from afar. It's full of cute and endearing moments as the reader tries to get closer to Douma without being too obvious. It's a really heart - warming read.