S12, EP24 "The Stockholm Syndrome"
Bernadette and Wolowitz leave their kids for the first time; Penny and Leonard try to keep a secret; Sheldon and Amy stick together; Koothrappali makes a new friend; the gang travels together into an uncharted future.
S12, EP10 "The VCR Illumination"
A VHS tape from Sheldon's past inspires him not to give up; Bernadette turns into a pageant mom when she tries to help Wolowitz with his Magic Castle audition.
S12, EP9 "The Citation Negation"
Sheldon and Amy are devastated after learning from a Russian paper that Super Asymmetry has already been discovered and disproved; Bernadette wants to beat Howard in a popular video game.
S12, EP8 "The Consummation Deviation"
Sheldon tries to bond with Amy's father, but when Wolowitz lures Mr. Fowler away with magic tricks, Sheldon has no choice but to bond with Mrs. Fowler; Koothrappali and Anu try to get physical for the first time.
S12, EP7 "The Grant Allocation Derivation"
Leonard is caught between a rock and a hard place when he becomes responsible for distributing extra grant money; Bernadette turns the backyard playhouse into a hideaway to get away from her husband and kids.
S12, EP5 "The Planetarium Collision"
When Amy doesn't have time to work on super-asymmetry, Sheldon goes to great lengths to ensure she's available; Koothrappali doesn't want Wolowitz to join him in hosting a show at the planetarium.
S12, EP4 "The Tam Turbulence"
When Sheldon won't tell anyone why he's never mentioned Tam, his childhood best friend, Leonard takes matters into his own hands; Bernadette and Penny take Raj's fiancee out to dinner to get to know her.
S12, EP3 "The Procreation Calculation"
Life gets complicated when Stuart starts bringing his new girlfriend home; Penny and Leonard talk about starting a family; Koothrappali explores an arranged marriage.
S12, EP2 "The Wedding Gift Wormhole"
Sheldon and Amy go crazy trying to figure out what "perfect gift" Leonard and Penny gave them for their wedding; Koothrappali decides to settle down and asks his father to arrange a marriage for him.
S12, EP1 "The Conjugal Configuration"
Sheldon and Amy's honeymoon runs aground in New York; Penny and Leonard discover they are uncomfortably similar to Amy's parents; Koothrappali insults physicist Neil deGrasse Tyson and starts a Twitter war.