In the bonus features, the creator/writer/producer admitted that they had no intention of ever letting Brian settle for one girl. They always planned on there being a "revolving door" of girl friends for him. Bad decision, I think. I think the high percentage of women who watched the show (the ratings were heavily female-centric) wanted to see Brian not swapping out girls every few weeks.
The unaired episode would have been the season finale for the first season with cliffhangers about Nicole and Angelo trying to adopt a baby, Majorie breaking up with Adam before leaving him at the altar, and Deena and Dave squabbling about their cheating at their daughters' ballet recital. This episode was better left unaired.