To her surprise, it took him a fair while. In fact, even the pair's two children spotted the change before their dad did.
In his defence, who is wandering around their house checking out pictures of themselves? That's some seriously American Psycho behaviour.
Upon discovering the switch, seven-year-old Maggie said: "Why are you marrying that man?"
Her mum explained that they are simply playing a 'trick' on her dad.
In another of the videos, Mairead tells 'Jack' that she's just off to drop the kids off at school and gives the photo a loving kiss goodbye.
"See you later darling," she said.
After three days had passed, Mairead had to up the ante, replacing the photo frame of one of the pictures, which eventually made her man take a closer look and realise what had been going on.
Obviously, he thought it was pretty funny.
"Shows how much attention I pay," husband Lee said.
He then added: "Might as well leave him up, he looks better than me!"
Those who have watched the video since it was uploaded have also found it pretty hilarious, too.
One commented: "This is absolutely hilarious, love it - and more so that the husband hasn't even noticed."
Another added: "Love how out of proportion the photos are."
Just imagine if it had been Harry Maguire, right?
A third person said: "Literally this is one of the best things I've seen on the internet today, 10/10,"
As for the real Jack Grealish, he and his teammates competed well at Euro 2020, but failed at the final hurdle when they were beaten on penalties by Italy.
Despite scoring early, the Three Lions - led by managed Gareth Southgate - succumbed to a second half goal and then held out to take the game to a shootout.
However, they missed three of their spotkicks and the title went to Rome, rather than coming home.
Still, Grealish did nothing to hurt his career, and has been linked with a high-profile, and incredibly lucrative, move away from his hometown club.
Whether he chooses to take that up, however, is still in the balance.
Featured Image Credit: TikTok/@thesteveos
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