in the seventh season, robin discovers that she is unable to have children. although she had always believed she did not want to have children, she is devastated by the knowledge that she no longer has the option. she lies to the gang about why she is depressed, saying that she has just found out she can't be an olympic pole-vaulter. ted senses that something more serious is going on, however, and surprises her by putting up christmas decorations in her apartment and comforting her as she cries.