I lost a whole pack like this once. had about 5-6 with 1 cub. came back from a few in game day trip farming and i had 2 wolfs and 1 cub left. wasn't sure what happened since all the meat/skins de-spawned. I eventually figured it must have been my hearths. I put up a half wall around them.
haven't lost a wolf since. They aren't very smart.