Jamie was a total tease
I know it's just a movie, but there is no way Jamie wasn't aware that she was a tease. With Dusty in high school he was a mess of pimples and hair barely able to sing one verse of a song that he wrote for her, and 10 years later all she can say is "I can't believe he wrote a song for me!" like she really thought that he just wanted friendship out of that.
I think Jamie was a jerk. She was totally playing with those guys acting like they were on board with being friends when they were practically screaming in her face that they were in love with her.
We're we really to believe that she was that stupid that she didn't know that they liked her? Chris said in the end that you should just put yourself out there and hope that that person likes you back instead of forcing them - hello! That's what he did in the beginning!