I had become completely captivated by this doll. Nitori uses 雛 here, and indicates it should be read as "her," but the character means young bird or doll.

I had become completely captivated by Hina.

Hina wasn't used to anyone and was always alone, so I...

let that give me some peace of mind.

I am the only one

who she can lean on, after all.

I am the only one

Still

she surely wouldn't want this situation.

For her, I'll remain just a friend, and shutter everything else in my heart―

For Hina, I'll remain just a friend, and shutter everything else in my heart―