Theory of dating
In "The Friendship Turbulence", after Amy has Raj check his dating site, he finds a message from a woman named Emily who wants to meet him.
Upon meeting Emily, Howard recognizes her because he had a blind date with Emily sometime near 2009 before he met Bernadette.
Amy and Emily exchange emails and find they have a lot in common.
They both went to Harvard University, are doctors, and like crocheting and Chaucer.
They meet again at dinner where she is now dating Raj.
Emily reveals she's okay with it and her friends love the story. In "The Anything Can Happen Recurrence", Raj and Howard watch the gore-fest "House of 1000 Corpses" because Emily wants to watch it with Raj.
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The four of them later give Sheldon a make-shift surprise party after Penny tells them it's his birthday.