Because of Carrie and everything Sami did to Carrie.
If EJ did this, I will be disapointed in the writers. I understand twists, but twists that make no sense are just poor writing. I mean why blame Ari? Why blame Stephano? I mean if you are doing this to teach Sami a lesson, why in the world would you be against your father who also hates Sami? If you were so "hurt" that you lost time with your daughter, why would you not go and see her? I mean this SL just has too many holes in it for me to swallow.