Steve Martin refuses to watch any of Selena Gomez's documentary for a very sweet reason

When she signed on to Only Murders In The Building, Selena Gomez became the third member Steve Martin and Martin Short didn't even know they needed.

The Apple TV doc looks into the singer's mental and physical health, and how a life of fame starting from a young age has impacted it.

An official synopsis of the documentary reads: "After years in the limelight, Selena Gomez achieves unimaginable stardom. But just as she reaches a new peak, an unexpected turn pulls her into darkness. An intimate study which spans her six-year journey into a new light."

She told cameras: "I'm going to be very open with everybody about this: I've been to four treatment centres.

"I think when I started hitting my early twenties is when it started to get really dark, when I started to feel like I was not in control of what I was feeling, whether that was really great or really bad."

Since then, Selena began seeing a psychiatrist who has taken her off all but two of her medications.

It was after this point that she signed on for Disney+'s Only Murders In The Building alongside Steve Martin and Martin Short.

Two seasons later, the three are incredibly close friends, but Martin recently confessed that he hasn't been able to watch his co-star's documentary just yet.

Speaking to The View, he revealed: "I kind of resist because I feel parental toward her or friendly or something and I know it's sad.

"Somehow I just don’t want to see her sad."

Later on in the interview, he added that he does plan to watch the documentary at some point, but he just needs to build up the courage first.