It's all my fault really
She comes to spend Christmas with her son and Alan at his new beach house and tells him a gorilla that Walden thought was imaginary was actually real. Walden becomes traumatized with his childhood memories and Robin arranges to have Walden meet with his long lost brother.
She turns against Walden for his own good by taking control of his company from him with the help of Bridget. When Walden fights back successfully with Alan she and Bridget try to woo Alan by buying him a $150,000 red Porsche and a happy ending in the men's room (sex). Alan disappoints the women and stays loyal to Walden which prompts her and Bridget to assault Alan.
She said it was her fault really she didn't abandon him, because she has a career. Walden even hallucinates Robin while having sex
After he broke up with Zoey, Walden took his anger out on his mother Robin, Alan and Billy Stanhope
She and Walden attend a charity for monkeys and he meets Lynda Carter there. She disapproves of Alan's attempts to woo Lynda. She and Lynda enjoy a threesome with Jenny and sneak out without Walden and Alan ever knowing.
Alan and Walden invite Robin, Evelyn, Jenny and Berta to break the news of their marriage, and like the others, Robin didn't highly approve of their engagement as Walden was marrying Alan so he could adopt a child.