How do you accept the fact that you can;t be friends with everyone that agve you a good feeling when you talked?

I met a girl from 1st semster of uni, she aske dmy number and sat next to me. I too, then 2nd semster came, more distanat and not showing energy taht she want to talk to me anymore. How do i move on ? I like being firends with most people, but it's hard when i;m at 7 th week and struggles to do it. when most people i knew were gone ?