In discussing marriage with David, Ann reveals her age to be 35 and says she was married the first time at age 18. This is only slightly different from her observation in the first season that she spent the first 17 years of her life under the control of her father and the "next 17" under the control of her husband.
This is the next-to-last episode where Richard Masur appears as Ann's boyfriend, David. After this, David disappears for four years, showing up only once more, in the sixth season, after Ann has moved on to someone else.
Reportedly, Richard Masur learned that the producers planned to keep the character of David as a nonsexual boyfriend (rather than Ann's lover or husband), who would just hang around Ann's apartment and keep getting rejected, and he thought that was unrealistic and emasculating, so he wanted out of the show.