Well well well before. They never showed his father at the beginning of the show. I think they planned on having them divorced all along. And frankly, that's where Sesame Street screwed up, as far as the Snuffy thing was involved. Of course, then there was his baby sister (which they don't even show anymore), and they couldn't have easily said "Oh yeah, he left when the baby was born." If they basically said "Gee Snuffy, I never seen your father before." and Snuffy used that to talk about divorce, it wouldn't have been such a problem.