How about Boy's school? Do you have the same idea about this?
If so , there should not be as many as elite schools which are the Boys and Girls school.
Just look around that it still has many opportunities for the girls to contact with boys socially and physically.
Don"t worry about it.
regards
I also had been studying in a girl school for 13 years. I don't see any problem with single sex school as there are different ways to meet opposite sex for normal social interactions nowadays.
I was graduated from girl's school too! But most of my girl friends were getting married at appropriate age with kids. For those who did not get married till now, some were from girl's schools BUT some were from co-educational schools. So, I don't believe studying in a girl's schools poses any adverse effects in the children's psychological development as such.