Why are girls doing this?

They say that boys are not loyal to them and would leave their girlfriends for other girl, its totally not true, furthermore, they are who arent loyal to boys and would leave any boyfriend for another, they dont value us and they are so uppity nowadays, all my friends would DIE for their girlfriends, and guess what, one of my friend's girlfriend left her, for other boy, and i see facebook like pages like "There arent any normal boys who would be loyal for their girlfriend" and such, im just getting sick of this... seriously what the f*** are they talking about? They are who leave a relationship not us, still they behave like we boys would've hurt them in deep heart, wtf?? Can someone explain this utter sh!t to me please?