Girls today have access to better opportunities than their mothers...who were better off than their grandmothers etc.
Basically, women have fewer obstacles in reaching their potential. To do this, western culture as a whole has pushed "girl power." Most teachers in school are female and a healthy portion of administrators are female.
Boys that have a learning style more similar to girls (able to focus and sit still while learning through discussion and reading) are able to excel.
Boys that are more hyperactive and need more hands on instruction, competition etc., struggle. Sitting still and listening to the teacher doesn't work for them and they need to be engaged in a different way. Educators have to mix up styles so that all kids can be reached. Since most educators are young (white) females, we tend to have classrooms setup in a way that favors the learning style that appeals to young white women.
That's why Black, white and Latino boys keep falling behind relative to their female counterparts. Asian boys and even immigrant African boys get strict discipline at home, that discourages acting out even if they would learn better in a different environment.