Come apart and fall apart can mean the same thing; something that separates into multiple pieces. Come apart is either intentional or unintentional: - The table comes apart to make storage easier (intentional) - My trousers came apart at the seams (unintentional) Fall apart is normally unintentional: - The table is falling apart (it's breaking) Tear apart means to deliberately pull something apart, into pieces/bits. To destroy it: - The cushion is ruined. My dog tore it apart. It can also be used somewhat figuratively: - I'm going to tear apart the house until I find my keys.