THE woman's long black hair whipped across her pale face as she danced to punk rock at the bar. She seemed to be the life of the party. Little did she know that she was igniting a girl crush. Susan Buice was watching, and she was smitten. Ms. Buice, 26, and the dancer (actually a clothing designer) happen to live in the same Brooklyn apartment building, so Ms. Buice, a filmmaker, was later able to soak up many other aspects of her neighbor's gritty yet feminine style: her layered gold necklaces; her fitted jackets; her dark, oversize sunglasses; and her...