Family and matrimonial problem

I’m pursuing a very long relationship with someone and now we want to settle down he wants to buy his own flat as his mother is not supporting me neither she is welcoming our union. The guy previously bring me in his home and I stayed with him and his family for 3 months during the time when his father was hospitalised and after that died. We thought we will do registry and maki it legal but his mother and married daughter created a lot troubles for which I need to leave his house and from then we are living separately. During this he has given me A sum of 5 lac rupees. Now it’s been one more year we are still struggling my father passed away and he stood by me always when no one is there. Now he wants to buy a flat for us living together away from his family. For that he wanted me to give him back 5 lac rupees which he gave. I told him I will give you but first you do the marriage registry but he told me we will do it after purchase and will make it legal. What shall I do now?