both families being happy

Both families being happy with the nikaah

Q: I like one girl. I met her three months back. I did istikhara at the starting and now after three months my parents went to there place and after that they ask our well know mufti to tell us if it is good for us or not. We gave him the names of both families and he said its not good for you but I love her. Can I go against this decision or not? Please help me. We have to inform them tomorrow about our decision.