Bear the cat was confused when his kitty sibling Boo passed away – then his owners caught the grieving pet doing something shocking.

Boo had been buried in the family's backyard under a small cross.

At first, Bear would just sit by his sibling's grave, not understanding why his playmate didn't come back out from under the ground.

Then one day Bear was seen desperately trying to dig in the grave.

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A video captured the whole thing, captioned, "My heart can't take this pain anymore."

The clip has gone viral at 2.3 million views and counting, and TikTok users took to the comments to express how Bear the cat had made them feel.

"Grieving a pet is hard enough but watching your pets grieve is like a powerbomb to the soul," one commenter wrote.

Others thought that maybe he was trying to play with his friend one last time.

"He is playing with him. One last play I guess like the other cat is saying its final goodbyes," said one.

Another commenter wrote, "A love like that never dies, he's just playing with Boo, cause they see the spirits we don't."