I think society is more tolerant of gay female sexuality, than any other. After all, alot of straight men think 2 chicks going at it is "HOT". If the situation were that of a gay male 19 year old and a 14 year old boy, I doubt they would refer to them as "boyfriends". They'd label him a predator.
The crazy thing is, I think that is because of our society's lingering sexism. Men are supposed to be the aggressors. Therefore no man involved equals no potential for real harm. It a view that harms boys (especially boys abused by women) and a view that minimizes the pain of girls abused by women.