Answer:
(Fatwa: 341/47/TH=1431)
It is unlawful and haram for both to love each other in this way, and no Nikah will take place without legal witnesses according to Shariah. If, according to Shariah, there is no hindrance, then ask the sister to live with him after valid Nikah, otherwise to keep away from him completely.
Allah (Subhana Wa Ta’ala) knows Best
Darul Ifta,
Darul Uloom Deoband
