Long story short, while Delilah was working two jobs to support them Steve was trying, and failing, as a musician. Del eventually had enough and kicked him out of her life and Aki pretty much disowns him as a dad.
However, he recently resurfaced once he heard of his daughter's successful career as a modelling agent. He decided to start his own, as competing with Aki seemed like the best he could think of to get closer to her. The career is going well, but not so much the daughter thing!