As I heard, Allah (SWT) made pair for everyone. Whatever we love or do affair it will no use. The girl selected by Allah (SWT) will come to us anyway. Is it right? Those who don't marry, what about them? Did not Allah (SWT) made any pair for them?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

We do not know any evidence proving that Allah has created a known wife for every man. However, Allah has predetermined every thing that happens in this world. Therefore, a person never marries anyone except the one who has been predetermined by Allah before creating them. This does not mean that one who intends to marry should give up all efforts. But one should try his best and, no doubt, that at the end only that which Allah has Predestinated Will happen.

Allah knows best.