The Big Bang Theory': Penny Finally Tells Leonard She Loves Him (VIDEO)

Leonard being insecure in his relationship with Penny is nothing new for "The Big Bang Theory." But the outcome this time around was something neither one of them expected. When Penny partnered with a British guy for a project in her class, Leonard was consumed with insecurity and jealousy.

So he made a complete fool of himself by following the guy down the stairwell and talking about how "tough" Penny's boyfriend is. The problem is, as Penny later pointed out, the guy knew Leonard was her boyfriend. His picture is hanging on her refrigerator.

When they finally talked about it in the hall while she was on her way to work, Penny's frustration led to an unexpected moment of honesty.

"You are the one I’m with," she said. "You know I love you, so will you please relax? You’re driving me crazy!"

She almost didn't catch it, but in the middle of her tirade she said those three magic words to Leonard for the first time ever. Quickly, so they both wouldn't start bawling, they decided not to make a big deal of it and Penny bolted off to work.

Fans will have to wait until next week to see what happens next between them. Catch "The Big Bang Theory" on Thursdays at 8 p.m. ET on CBS.

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