Victor’s father is supportive and kind to Victor. He takes Victor into the mountains when Victor is grieving over Justine’s death and his guilt. He travels to visit Victor when he is imprisoned for the death of Henry. When Elizabeth dies, he dies shortly afterwards of grief.
Victor’s father is yet another stop on Victor’s path to total and complete loneliness. The monster didn’t even have to off him; he just went voluntarily. But in all seriousness, Alphonse emphasizes that loneliness really is the worst thing you can suffer. He dies of grief when he loses a family member…and you could easily argue that certain other characters (ahem, Victor, ahem, the monster) die for similar reasons: the grief of isolation.