Walden suspects his new girlfriend is cheating on him. Meanwhile, Alan gets even more intertwined in Lyndsey and Larry's relationship when he starts dating Larry's sister, Gretchen (guest star KIMBERLY WILLIAMS-PAISLEY).
Walden is delighted when Kate flies to LA and asks an appointment on Valentine's Day. Alas, she only wants friendship, still prefers 'Sam' and now has just a busy calendar as Walden, so no next date can be booked. For once, Alan decides to 'spoil' Lyndsey on Valentine's Day by booking a hotel suite he can't really afford. But pubic grooming on himself goes so bad she has to drive him to hospital instead. Rose is unsuspecting Kate's new business partner, who lures her to China.