All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
Swearing not to have sexual intercourse with your wife does not make her unlawful to you. If you have sexual intercourse again with her, this means that you broke your oath and therefore you have to expiate for breaking your oath; for this please refer to Fatwa: 81501.
However, if you do not have sexual intercourse with her again, it would be permissible for her to take the matter to a Muslim judge, if any, or to any Islamic centre which would give you the choice either to have sexual intercourse with her or to divorce her. Allaah says (which means): {Those who take an oath not to have sexual relation with their wives must wait four months, then if they return (change their idea in this period), verily, Allaah is Oft-Forgiving, Most Merciful. And if they decide upon divorce, then Allaah is All-Hearer, All-Knower.}[Qur'an 2:226-227].
Finally, it should be noted that the two spouses should be keen on preserving the stability of marital life and understand each other in solving the problems that might occur between them.
Allaah knows best.