Why didn't my prayers work?

I'm muslim, and im a 14 year old girl im on my period so i was making dua's last night, and why dont they work?? Today i found out a black girl in my high school is also muslim, but she doesnt dress modestly and she said shes allowed to date, and that Muslims just worship a different god from christians. so my dua was to date some1, and my previous ones worked but this one i REALLY wanted, and this one god didnt help me, in fact the person i accidently told him im muslim i cant date and the black girl said she can and he started touchinf her why did this happen, now he'll never ask me out ill pray 4 him to forget