Two dying writers wrote bestselling memoirs. Then their partners fell in love.

There’s a love story entrancing the internet at the moment.

Lucy Kalanithi and John Duberstein recently did an interview with The Washington Post which has since gone viral. Why? The two have an unconventional and simultaneously heartbreaking and heartwarming love story.

It sounds like something out of a Hollywood movie, only this is very much real life.

Both Lucy and John lost their partners to cancer. Paul Kalanithi died of lung cancer at just 37 while Nina Riggs passed away from breast cancer when she was 39 years old.

Both writers authored memoirs of their final years battling the disease. Paul's When Breath Becomes Air was published posthumously in 2016 with Nina's The Bright Hour also published posthumously last year.

The two were instant bestsellers and critically acclaimed, often coupled together in lists, essays and discussions.

They also helped bring their spouses together before they eventually fell in love.

"I’m still surprised. I'm surprised by how ridiculous it is and natural it is at the same time," Lucy told The Washington Post.

It was because of When Breath Becomes Air that Nina knew Lucy had gone through what her husband was about to, and she recommended he contact her. The two women had been in contact since 2015, even writing a recommendation that appeared on the back of The Bright Hour.

Two days after Nina passed away, John reached out to Lucy, sending her a long message, with questions like "How do I write a eulogy? How do I not go insane?"

The two kept in contact, speaking regularly over the next few months, with Lucy becoming a "guardian" for John. In April, a work trip for Lucy to near where he lived meant meeting for the first time in person.

It was "intense" and the pair had "a lot of chemistry". It was clear how the pair felt about each other.

Aside from their children - John and Nina had Freddy, 10 and Benny, eight while Lucy and Paul had Cady, three - they kept their relationship a secret, before opening up to friends and family at the end of August.

Listen: These are the things the dying regret. Post continues after audio.

Both acknowledge the difficulty of juggling the love in a new relationship with the grief of losing the partners they thought they'd be spending their lives with.

However John told the paper he finds solace in the fact Nina essentially matched him with Lucy. A sign of approval if ever there was one.