Without going much into spoilers, we see that Maul in latter part of his life (after Clone Wars) had two main motivations : his hate against Obi-Wan Kenobi and his hate against Sith (i.e. Palpatine) . Kenobi of course cut him in two, and Palpatine killed his brother, mother and basically ruined his life.
Yet, Maul did get some revenge against Kenobi: he killed his love Duchess Satine Kryze. Maul specifically said he doesn't want Obi-Wan dead, he wants to see him "share his pain". Yet, we see Maul later compulsively searching for Kenobi, almost driving himself mad. What is the reason for his continuing hate ?