بسم الله الرحمن الرحيم
(Fatwa: 1315/1315/M=11/1434)
If that person swore in the name of Allah that he would not continue the relation with that woman anymore and now wants to marry her then he may marry her. However he shall have the sin of breaking his oath and therefore will have to pay the kaffarah of his oath. Oath cannot be taken back. Also it is unlawful to talk to any strange woman before nikah and to love her.
Allah knows Best!
Darul Ifta,
Darul Uloom Deoband
