Been a while since I read them so I honestly don't know if they're worth recommending, but...
https://mangadex.org/title/521/shi-ni-itaru-yamai
It's definitely torturous, although it feels a little forced to me now.
https://mangadex.org/title/269/natsu-no-zenjitsu
Not a tragedy, but it certainly broke my heart when I read it.
Romance isn't really my cup of tea though so I don't know a lot.
Edit: Can't I make text links work.