Book about a grieving woman who loses her partner

This might be very difficult because I really don't remember much, and I never finished the book. It's the story of a woman who loses her partner in an accident (?), and is unable to cope with the grief. She lives in a house alone, and iirc doesn't have many friends. I think this woman also had a sister. She may or may not have felt responsible for her partner's death. The book has a strange (not in a bad way) writing style, and I think some pages/chapters were designed very differently.

I don't know if this is relevant at all, but I was reminded of it while reading Eleanor Oliphant is completely fine.

I will be grateful for any help, thank you.