Sandi Robbins is an actress hired to play the character of Elaine in the pilot of Jerry.
She is extremely promiscious and has a huge attraction to Jerry himself. She fools herself into thinking that she and Jerry are dating, and when he rejects her advances, she believes he is breaking up with her.
Robbins is a method actress, trying to learn as much as she can about Elaine. This may also explain why she goes through the motions of dating and breaking up with Jerry before the pilot is taped, so that in her mind she can more effectively play the role of Elaine.
Sandi Robbins is portrayed by Elena Wohl, who appears in “The Pilot”.