While there were other female characters who had brief flings with Robert, there was no one permanent character who followed Suzie Plakson as Robert's love interest.
However, there was one recurring character who was a potential love interest for Robert after Bonnie:
* Amy: Played by actress Monica Horan (who also plays Debra's sister, Amy Barone, in the show), she was a therapist who briefly dated Robert. However, their relationship was ultimately not pursued.
Ultimately, the show focused on the Barone family dynamics, and Robert's love life was not a central focus. He remained single for the majority of the series.