Illinois - Three-year-old Mack recently had to cope with the death of his best friend, Shenzi the dog, and TikTok users are weeping.

Recently, Mack's mother watched him sitting in front of the refrigerator in the kitchen.

She recorded what the toddler was doing in a bittersweet video.

The post starts with a few scenes of Mack and Shenzi cuddling.

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Then there is a leap in time: in the last scene, the dog is no longer there.

Instead, Mack is sitting in front of the fridge with a photo of the deceased pup hanging on it.

The boy stares intently at the picture, seemingly pondering why he now has to be without Shenzi – and where she is now.

In an interview with Newsweek Mack's mother has now explained how this moment came about and what happened afterwards.

She discovered her son in the kitchen and watched him for a while before deciding to capture part of it on video, Erin Sullivan said.

"It was a very sweet moment because I knew it was his way of grieving her," the mother explained.

"He wasn't crying, but the way he was analyzing the photo made me think about how much he missed her in that moment."

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However, the mama didn't leave her little boy alone with his grief for long. After about a minute, she went to him and gave him a hug.

But the loss of the dog is not only hard for Mack.

"She still feels so present in our lives and sometimes it hits me like a gut punch that she's gone because I still feel her around," Sullivan said.

"I hope I feel her presence for many more years to come because in a way it's very comforting."