Lovebird's biting

My bird has recently started a very agressive biting habit. She is biting my friends and family for no known reason. She also recently started biting me too. I don't know what has caused this behavior. She is out of her cage a lot of the time and gets plenty of attention. Also, she has not layed any eggs in the past year. She has only ever layed 1 clutch and she is around 3 years old. Could that have something to do with her biting?