GOKAAAAI... SILVER!
@E-123
Well, it was more that he felt like a failure because he hadn’t achieved his own dream of becoming a Pokemon Master… so he left Delia and Ash on their own. That’s why Ash acts so miffed when his mom mentions his dad in the second episode.
This was most likely meant to go somewhere, but since the original head writer left the series during the Johto episodes (and then died in 2010), it naturally never did.