The fallen angel

A young angel maybe in her late teens or early twenties could suddenly fall from grace with no purpose other then maybe she was watching over someone, started to develop feelings for him despite being up in the heavens. So to punish her or teach her a lesson she could be kicked out of heaven, she would still have her wings etc but she would gradually learn how to become mortal then eventually have her wings clipped as punishment for fornicating or falling in love in general.