Estrangement?

I recently turned 30 and sometimes feel like all my friends are settling down, living “normal” lives, while I have a lot of difficult baggage and never had a partner. Can anyone recommend a book that is around these themes, maybe themes of loneliness, estrangement, changing with ages, comparing. For example I like the short story “sisters” in Antarctica by Claire Keegan, but I am very open regarding genre, interpretation etc:)