Thelma and Louise should be appalled.

Almost 25 years after their epic road movie attacked “conventional patterns of chauvinist male behavior toward females” (in the words of one critic), here arrives “Fifty Shades of Grey,” perhaps the most successful anti-feminist movie ever made.

The runaway best-selling novel is now a juggernaut on the big screen, driven by overwhelmingly female audiences that accounted for its record-breaking opening weekend.

The dirty secret of “50 Shades” is that, underneath the kinky exterior, it’s a formulaic romantic fantasy.

For all its notorious boundary-pushing, it is the distilled essence of decades worth of Harlequin paperbacks, with hyper-stereotypical gender roles pushed to the point of perversity (figuratively and, of course, literally).

“Fifty Shades” is a version of the age-old Boy Meets Girl story, except the Boy is a dangerous creep.

As countless millions already know, the story centers around 27-year-old businessman Christian Grey’s seduction of ingenue Anastasia Steele, a college student.

He is older and wealthy. She is young and poor. He is experienced and controlling. She is naive and trusting. He’s the strong, quiet type. She’s vulnerable and wants to talk. He owns a helicopter. She drives a VW bug.

He overawes her. When Anastasia is first in Christian’s presence, doing an interview for her college newspaper as a favor for a friend, she practically collapses into a puddle of helplessness before the sheer force of his Alpha Dog personality.

Later, she needs him to save her from the unwanted affection of a college friend.

Her road to adventure and material plenty (glider rides, gifts of expensive cars, etc.) runs entirely through him.

All this is a bit much, before we get to the fact — and, obviously, this is what sets “50 Shades” apart from other romances — that Christian wants to physically and emotionally dominate her and hit her for his own pleasure.

No wonder some feminists are inveighing against the film, and this time, the Sisters have a point.

As much as it can, “50 Shades” seeks to sanitize the S&M. Christian wants Anastasia’s consent in a written contract so elaborate, it could be negotiated by high-powered lawyers, provided they had a strong stomach for graphic sexual content.

But there’s no sugar-coating what Christian is about. His seduction of Anastasia is emotionally manipulative, his drive to control her is abusive, and his pursuit of her — showing up unexpectedly at places where she is — could easily be considered stalking.

If anything like this happened in remotely more realistic circumstances, the proper response to Christian’s obsessive attention would be a good kick in the groin, followed by a restraining order.

Not to mention a referral to a first-class psychiatrist. The roots of Christian’s desire to hurt women is his own abuse as a child.

Anastasia, in her wide-eyed way, wants to save her Byronic romantic hero from his demons, but that would be better left to a professional with years of training and lots of time to work with an emotionally damaged client.

The lesson of “50 Shades” should be: Ladies, don’t try this at home.

In real life, trying to reform manipulative and abusive men only ends in tears, and becoming subject to sexual humiliation only brings humiliation.

The edge is taken off “50 Shades” by its sheer ridiculousness — the movie is punctuated by moments of inadvertent hilarity — and its fairy-tale ending. Anastasia maintains her identity, even though Christian wants to obliterate it.

And, over the course of the three books in the franchise, Christian Grey is indeed reformed and tamed, and Anastasia forms a happy family with him. It’s Ward and June Cleaver, via a pleasure room that looks like something out of a Restoration Hardware catalogue.

Needless to say, there are easier routes to marital bliss, and they never involve anyone like Christian Grey, who gives the patriarchy a bad name.