Her husband was inaugurated on a Friday. By Monday, America’s new first lady had become an internet meme. An eight-second gif that showed her flashing her husband a broad smile when he turned to look at her, which quickly evaporated when he turned around, went viral within hours.

The narrative quickly caught on. #FreeMelania trended across social media. “Melania, blink twice if you need help!” urged some of the banners on display at the Women’s Marches held the day after the inauguration. Liberal media outlets weighed in. “Watch this clip of Melania Trump during the inauguration then pray for her” tweeted the Huffington Post. Slate offered us a “detailed forensic analysis of Melania’s creepy, devastating inauguration smile/frown”. An image of the Tiffany gift box she gave Michelle Obama – open and containing a note pleading “HELP” – was shared thousands of times.

Much of this was couched in ironic liberal jest. Because yes, making light of domestic violence is simply hilarious. But some have gone so far as to earnestly argue that we should be genuinely concerned for Melania Trump’s welfare. The feminist writer Laurie Penny wrote a column last year imploring us to feel sympathy for America’s “first victim”. She speculates about Trump’s smile as the smile of a woman who is afraid; about her speech on cyber-bullying as a veiled cry for help; and paints a picture of her as someone “with a gun discreetly pointed at her back, with her necklines so high her clothes seem to be trying to strangle her and that rictus smile that never reaches her eyes”.

In jest or in earnest, there is a rank hypocrisy here that sits uncomfortably with me. It’s deeply sexist to erode a woman’s agency, imposing an abuse narrative on her to fit your own political take on the world, on the basis of little more than conjecture.

It hardly needs pointing out there are any number of reasons Trump might have momentarily frowned. A quick online search throws up dozens of stills from past inaugurations where the stiff awkwardness of an incoming presidential couple contrasts starkly with the easy grace of their soon-to-be predecessors, much more comfortable in their skins.

And reading a self-professed feminist commenting on another woman’s high necklines left me feeling more than a little queasy. At the heart of #FreeMelania sits a patronising assumption of a feminist false consciousness: how else could a woman marry a blatant misogynist, and defend his birtherism and anti-immigration positions, unless she’s a puppet in an abusive relationship?

There’s nothing new about women in public life being held to a very different standard to men in terms of their appearance and how they conduct themselves in front of the cameras. But #FreeMelania has been perpetrated by people who really ought to know better. People who would be the first to call out men such as Trump who pass off their disgusting remarks about sexually harassing women as “locker-room talk”. Or to challenge the idea that Hillary Clinton might be too old to be president, when she would have been younger than Ronald Reagan was at his inauguration.

None of this is to distract from the enormous fight feminists have on their hands, with a self-confessed, pussy-grabbing misogynist, who thinks nothing of trashing women based on their looks or signing away their reproductive rights, now firmly entrenched in the White House.

A protester at the women’s march in Washington. Photograph: Nikolay Doychinov/AFP/Getty Images

But #FreeMelania is neither just a harmless joke, nor just an opportunity for some women superciliously to question other women’s feminist credentials in a way that distracts from the real fight. I think it betrays an important truth about how discrimination manifests itself.

Our collective dirty secret is that none of us is entirely above discriminating against others on the basis of their gender, ethnicity, class or age. Very few of us are immune to the unconscious bias that creeps in as a result of the way we’re socialised from early childhood. If you don’t believe me, take an online implicit bias test. I did and it showed that I have a slight unconscious gender bias. If I’m totally honest, I know it, too. I can’t be the only person who sometimes catches myself horrified and mid-thought in a social situation, realising I’m about to make an assumption about someone because of their age or gender.

Some #FreeMelaniers may have been fully aware and not particularly bothered they were perpetrating a sexist trope. But I bet some didn’t even think about it, which is an important reminder that combating sexism isn’t just about going on marches, campaigning for change and demanding others behave differently. It is also about practising what you preach.

This is where feminism on the left sometimes falls down; when people get so caught up in the self-righteousness of their own political narrative that they forget to also hold themselves to account. Feminists should constantly be asking themselves difficult questions. Am I supporting the progression of younger women in the male-dominated environments in which I work? If I’ve bagged myself a spot at the top table, am I doing what I can to make sure there are other women there? I bet if a lot of us were straight with ourselves, we’d admit there’s more we could do.

“When they go low, we go high,” declared Michelle Obama in one of the best political speeches of last year. Some on the left seem to think that what they do is, by definition, going high. #FreeMelania is a useful reminder that going high isn’t just about loftily calling out the behaviour of others from our morally superior heights. It must also be about holding up a mirror to ourselves.