Continuity mistake: Al enters the house at 3am with Lucky. It is sleeting outside and there is snow all over the front and backyard. Later that day, Al is in the backyard, no snow to be seen, and grass and bushes in full bloom.
Continuity mistake: In this episode Al is building a dog house for Lucky. In Season 9 episode User Friendly, we are shown that there already is a dog house, which has electricity and a light.
Answer: It's implied that Steve filed for divorce since in s04e16, "You Gotta Know When to Hold 'Em", Marcy says that Steve is suing for alimony. Alimony is something that has to be requested when filing for divorce. Although the show doesn't spend time on the actual legal proceedings of their divorce.
Bishop73