YOU SAID:
he hated that he hated what she hated about hate
INTO JAPANESE
彼女が嫌いなことを彼は嫌いだった
BACK INTO ENGLISH
he hated what she hated
INTO JAPANESE
彼は彼女が嫌っていたものを嫌っていた
BACK INTO ENGLISH
he hated what she hated
You've done this before, haven't you.