Express the views (ijab-o-qubul) both boys and girls without any witness, will it be allowed as a marriage?
بسم الله الرحمن الرحيم
(Fatwa: 992/774/H=1434)
If the boy and girl do ijab-o-qubul (exchange of formal words of nikah) in privacy and there are no Shariah witnesses in the meeting then nikah shall not be valid. It is so mentioned in Fatawa Shami etc.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband