Of course Fred would understand even without an explanation. There were a lot of reasons that Sam had married her, and this was one of them. He managed a sad but hopefully reassuring smile as he looked down at her.
"Life goes on, right?"
It wasn't exactly an answer, but they would do what needed to do. They would continue to carry on.
"Come on. Let's go home. Maybe we can look through my books and see if there's anything that might shed light on what's happening here."
If they could find the cause... maybe they could stop it? Or reverse it?