The dream is a Shaytaani one. The Shaytaan has whispered (waswasa) of evil in you and that had led to your illicit and Haraam relationship with the girl.
You should terminate your relationship with her and make Tawbah (repent) and Istighfaar (seek forgiveness). If you love the girl, discuss the matter with your seniors and consider marrying her. If you cannot do that, then do not have anything to do with her. Nobody can predict anyone’s destiny. That is known only to Allah.
and Allah Ta’ala Knows Best
Mufti Ebrahim Desai