this boy found a large cocoon and took out the butterfly girl that was in it. he makes her live with him she develops stockholm syndrome but she later escapes. she lives with a homeless person who I think dies and caterpillars come find her.

It's Ogeha.

it is, thank you.

I also forgot the name of a manga I read some years ago.

I'm not sure if I'm mixing up different storys.
This is what I remember:

It's a love story. The girl is shy and doesn't follow her dream to make music. She tries to do what her parents want. It changes when she meets a boy, who has some problems in his home.
I think he lives separated from his family. He encourages her in her dream. His hobby is either astronomy or photography, I think.
At the end of the story she plays the piano/orgel at the improvised wedding of eloped friends. Also her then boyfriend proposes in a church, where she has to find the heart-shaped ring on the walls, where he had projected a night sky.

I hope can help me with this.