What Happened?

Five year old Jack and six year old Alex were playing in the sand box. They were happily piling sand into their plastic buckets, in preparation for the sand castle they were going to make.

“Jack, we’re always gonna be best friends, aren’t we?” Alex asked. “We’re always gonna make sand castles together?”

“Duh, Alex.” Was Jack’s simple reply as he continued shovelling.

Alex was hesitant to reply. He looked down, his brow furrowing, biting his lip in confusion. He wanted to be best friends with Jack, didn’t he? After a moment’s consideration, he looked up and smiled. “Good.”

Ten years later, the two of them are walking towards Alex’s car after school. They were smiling, joking and pushing each other every now and again, stopping once they reached the vehicle.

“We’ll always be best friends, you know that, right?” Alex said, looking at Jack over the car.

Jack smiled. “Whatever, just take me home.”

Alex smiled too, climbing into the driver’s seat. He started the engine and began to drive away.

Now, Alex is sat at home, crying, without his best friend. Jack had always said they’d be best friends forever, and Alex had always believed him.

What happened?