Ferris Bueller???
C'mon, everyone knows Jennifer Grey was in Ferris Bueller!!! That among many other examples makes me just think Tina is a complete fool. How she's so certain of something that she's willing to bet money on it even though she's dead wrong.
That said; I understand her point how she made this guy over to be more fit, handsome, confident and ultimately ended up gaining success as a result. I get how she now feels cheated, like she did all the work... But the whole time she could have had him she didn't want him. She mocked him, rolled her eyes at him and rejected him repeatedly. So now that he moved onto someone else and she's desperate to have him back she just seems even more pathetic.