What will be the in universe reason why Harrow hasn't returned to his children?

"If I pretend to be dead, my sons will be forced to grow as people without my help. This will prepare them for the real world."

Now that they're traumatized from fighting several wars and Satan himself, he plans on returning for one of their birthdays as a surprise. This is why he hasn't returned yet.

Viren and Aaravos would seriously have some strong competition for the father of the year award if this was true 😂