Marriage not allowed

Date: 7/25/2017

There is a matchmaking process..i met Nate ,But my dad dint approved him .so i have to drop the proposal. That night i dreamt that Nate will date my sister. After a while Nate and my sister started dating each other( i said to myself that my dream is turning into reality in actual dream ) Now my sister is geting married to Nate .I explained her dad won't approve .(she thought i am just jealous) My dad met up with me, Warning me about Nate .He just looked me in eye and warned me "That man is not good for you ". How can i explain it to my sister?