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Did TAYLOR SWIFT write her entire "Red" album after she gave up her virginity to JAKE GYLLENHAAL and he NO-SHOWED her birthday party?  That's what the not-always-reliable RadarOnline.com says.

 

A source says Taylor was saving herself for marriage, but Jake convinced her he was worth it . . . quote, "She thought she was going to marry Jake, that's how in love she was with him."  At the time, Taylor was 20 and Jake was 33.

 

In December of 2010, a few months after Taylor let go of her purity, she threw herself a 21st birthday party.  Jake was all set to be there . . . or so she thought.

 

The day of the party, he WENT OFF THE GRID.  He didn't call, he didn't text, she couldn't find him, and he never showed up.  A source says, quote, "She locked herself in the bathroom and cried the entire night."

 

The source adds that "every word" of the "Red" album was inspired by the ensuing breakup.  Especially the song "The Moment I Knew", which is literally about being stood up at a birthday party by "the one who means the most."