Beautiful story , sad ending

As a fan of Japanese series , I randomly watched it. It’s a beautiful story. At first i thought it’s very erotic but at the same time shows the intimacy growing between two people. I didn’t expected the ending and i felt so sad cause i loved that character. Not giving major spoilers.
It’s really beautiful to see , two people, completing each other , finally enjoying their life happily and than something like this happens . I felt devastated and heartbroken. Loved the acting and the couple. ?