For hours, Matt Sooter had been watching his two young children talk and play.

Maybe the conversation was about Queen Elsa or plastic Easter eggs — two topics his 4-year-old, Adalynn “Addy” Sooter, knew well. He doesn’t recall what the two were discussing that Saturday night at a hospice facility in Arkansas, where Addy lay dying after a long battle with Diffuse Intrinsic Pontine Glioma (DIPG), a rare tumor that starts in the brainstem.

But the father does remember the heart-wrenching moment that followed — when Addy’s 6-year-old brother, Jackson, told his younger sister good night for the last time.

Sooter, 29, said that Addy was tiring and that it was time for Jackson to head to sleep not far from his sister’s bedside. Jackson let his sister hold his hand, then he patted her forehead and said, “I love you.”

Sooter snapped a picture and posted it on Facebook on June 2 — capturing a heart-wrenching moment that has been shared across social media.

“A little boy should not have to say goodbye to his partner in crime, his play mate, his best friend, his little sister,” Sooter wrote in the post. “This isn’t how it’s supposed to be. But this is the broken world we live in.”