His father wants him to marry his cousin who is close in age to him

Alhamdo Lillah I am a practicing muslim and I am also involved in the work of Tabligh and Dawah. One thing that always gets me and makes me feel that I am not doing enough for my deen and my life hereafter is when I think about my Father. My Father is a good practicing muslim and it is from him that I have learned about Islam. I have three brothers all of them are elder to me and all of them are married. We had a great family and great atmosphere at home until it was time for the brothers to get married. My father wanted them to marry my cousins, but my brothers were against it and they were married to other girls who were not from our relatives. So now my father does not have the same attitude towards them and he always tries to elude them and ignore them. I was terrified to see him act like this as he is a staunch muslim  and respects Islam and it's teaching. Now it is time for my marriage and he wanted me to marry one of my cousins. Now the problem that I am facing here is that me and my cousin we were kind of close as we were of nearly same age and did most of the schooling together. So I have known her mostly as a good sister and now my dad wanted me to marry her and I was in a state of jeopardy. I am very much aware of the rights of one's dad and that he is the doorway to my Jannah. The problem with my dad is that he does not say anything and he just behaves as if I do not exist. He would talk to me and everything but like a stranger and infront of others he would behave as if nothing is wrong, but that kind of attitude is killing me and I think that he is really pissed off with me. The question is about my life and who I would like to spend my life with, but on the other hand I run the risk of spoiling my Akirah by making my dad unhappy. My question is how do I handle this problem? How do I get my dad to be the same old self as he was, please guide me in this regards