Gender segregated schools do not prepare children for real life
Schools are about preparing children and young people to function in life. Real life consists of a symbiotic relationship between males and females. The education of girls apart from boys and vice versa is highly detrimental to both sexes. The only other institution that separate the sexes in this way is prisons.
If girls suffer discrimination in mixed schools, then that is a matter that needs addressing in the mixed schools; it is not solved by segregation.