Tiny Dancer

(I used to write as xleglover and Flash of Stocking)
Sarah is a college sophomore and Mike is a grad student. Despite being opposites -- or may because of it -- they are best friends. Mike adores Sarah. But she's friend-zoned him.
Mike watches as Sarah has relationships with other men. Guys from college. Men she meets at Paradise, a men's club she works at to make money for school.

Sarah also gets involved with an older rich man in NYC - Jeremy - who needs a girlfriend sometimes to take to social events. But Jeremy has fallen for Sarah and is offering to make her dreams come true.
Mike watches all this from a distance. He watches as the girl he loves and adores is pursued by other men. And then, to his horror, he discovers he gets aroused watching Sarah with other men.
Read about Mike and Sarah in this second book of the Tiny Dancer series.