Rosenberg Syndrome
When with a woman, or about to be with a woman, your penis shrinks so as to prevent performance

or

blowing way too early so that your girlfriend leaves you as soon as she sees it, also called Pulling a Rosenberg
Isaac: Dude I heard that guy couldn't get hard for his smoking hot girlfriend.

Shay-Shay: Ya man he's got the Rosenberg Syndrome so bad!