Why did carine wonder if things would have turned out differently if chris mccandless had taken buckley with him?

In the book "Into the Wild", Buckley is Carine's sheepdog, and Chris McCandless loved him. He asked Carine if he could take Buckley with him to Alaska, but the dog was hit by a car and hurt. The dog died. Everybody including Carine wondered if the dog would be alive had he been home instead of with Chris.