Inside the scandalous real-life romance between two iconic 70s sitcom stars who played siblings

David Cassidy and Susan Dey starred in The Partridge Family as oldest son Kevin Partridge and teen keyboard player Laurie Partridge, respectively. The show transformed both actors into '70s teen idols in the all-singing-all-dancing sitcom.

The Partridge Family saw David and Susan, along with their three siblings and widowed mother, form a band and hit the road in a truly '70s school bus. The show aired between 1970 and 1974, for a total of 96 episodes across four seasons.

While David and Susan grew to be close friends, it was soon clear that Susan had fallen head over heels for her co-star – according to David, at least. He wrote in his autobiography Come On, Get Happy that his co-star was "hopelessly in love with him".

When the confession came, he apparently knew their friendship was doomed to fail. He explained that he thought of her as more of a sister. According to Shirley Jones' memoir, David "didn't reciprocate [Susan's] feelings. He didn't treat her well during that time, and it broke her heart."

David started his acting career in the 1969 Broadway musical The Fig Leaves Are Falling. A year later, he became a household name on The Partridge Family. His musical talent was put to good use on the sitcom and off-screen, finding hit success with tracks like 'I Think I Love You', 'Cherish' and 'Daydreamer'.

In 1971, he was nominated for a Grammy Award for Best New Artist as part of The Partridge Family and won Best Singer Awards in 1973, 1974 and 1975 from German magazine Bravo.

Susan was discovered through modelling photos in her teens. Despite having no prior acting experience, she became a teen idol and a household name. 

But Susan's acting talent took off in her adulthood, with the actress opting for dramatic roles. Her most notable later casting was in L.A. Law as deputy district attorney Grace Van Owen in the legal drama between 1986 and 1992. She earned three Emmy nominations and a Golden Globe for the role. 

David Cassidy was married three times throughout his life. He first tied the knot in 1977, marrying Kay Lenz and divorcing six years later in 1983. The next year, he said 'I do' to Meryl Tanz. The pair split in 1988.

He married his third wife, Sue Shifrin, in 1991 and remained married to her until 2016. They welcomed son Beau in 1991. He had an on-and-off relationship with Sherry Williams, with whom he welcomed daughter Katie.

Susan Dey first tied the knot in 1976, marrying Leonard 'Lenny' Hirshan. The couple welcomed daughter Sara Dey-Hirshan in 1978. They divorced three years after she was born, in 1981.

In 1988, Susan married television producer Bernard Sofronski on February 20. The pair remain married to this day, almost 40 years after saying "I do".