End of a friendship .

I know two girls they were best friends since childhood and no matter what would happen ,they would always take eachother's side but today in school after exam ,we all were waiting to get the door open so we all could leave well i was randomly looking at classmates than i saw one of them standing alone and her face was red ,she was looking terrible so i asked whats wrong ? "She said"nothing but i kept asking so finally she said I don't have a best friend anymore .I was really shocked to hear those words from her and the other girl she was standing with some other friends but she was smiling but i didn't ask anything from her because she was discussing answers of exam so i stayed quiet .I asked the previous girl why did you guys broke your friendship ,"She said"because that girl is pretty and smart And "i said" you're also pretty .After that she didn,t wanted to talk about it .I felt so bad that they are no longer best friends because i thought there friendship would stay till they were alive but today i just learnt that Friendships do have a end .