Sexy film “365 DNI,” billed as “the closest thing to porn on Netflix” by Decider, is the most popular lockdown movie on the streaming service.

The Polish-produced movie, which some say “makes Fifty Shades of Grey look PG” has attracted millions with its graphic sex scenes between a kidnapper and his hostage. Yet the success of the film — whose critics say it “romanticizes a forced relationship” — has confounded some sexperts, stunned by the puzzling plot and the yacht-rocking scenes between the Mafia boss kidnapper Massimo and his captive Laura.

Ralph Sutton, co-host of the “Sex, Drugs & Rock ’n’ Roll” podcast, told us, “Some sort of Stockholm syndromey love affair develops, but throughout the movie you have no idea how much time has passed. A few days? A few months? … And then after Laura almost drowns — there’s a sex scene on a boat [and] I swear I saw shaft.”

But, at the end, he “felt as unsatisfied as I am sure most women in my life have felt after they’ve watch porn with me … the only thing I wanted to do was rewind to the boat sex scene again to see if I really saw shaft.”

Alice Vaughn, co-host of “Two Girls One Mic,” which reviews porn, said, “Is it entertaining? Kinda. Is it problematic? You betcha … 365 DNI wasn’t written for an Oscar. The movie was created for women who want to watch porn, but don’t want to be judged for watching porn.”