Nobody understood. Nobody could even try to understand. Hermione's parents were obliviated, they didn't remember her, they were safe. Harry's family was dead. He didn't fear every second of his life that his brothers were dead.
That's why Ron listened to the radio. That's why Ron was so touchy. And in reality, that's the reason he left. He had to make sure he was alive.
What if it was Bill or Charlie? The people who helped raise him?
Percy? The obnoxious little prat that he missed so much?
Fred and George? His best friends? The ones who taught him about life? They were running Potterwatch after all.
Ginny? The youngest. His little sister. Harry's love. Hermoine's friend. What if she died? Could he go on?
So Ron left. So he had to go find them. He had to know something. Then he would go back to them.
If only Ron knew the next time he went to Hogwarts, he would be able to see the thestrals too.