Confusion about a relationship

Your father's sister will be your aunt. Your aunt's son will be your brother-in-law. That means his daughter will be your daughter-in-law. You will ber uncle. But you are telling me that both of you are of the same age. The relation will come under the Sapinda relation. As per the special Hindu Marriage act, this type of marriage is not legal. But if such marriages are allowed in your circle and nobody complains about the marriage, you will not face any problem. If any interested party makes a complaint, you may have to face the case.
I know many cases where a person marries his mother's brother's daughter. And no complaints will be raised in this regard. So you have to think about the practices there in your community in your area and decide. But if your father is not ready to accept your marriage and if you marry against his will he may take the same seriously and may file a case against the parents of the girl. If the parents of the girl are willing to the marriage, it is better to convince your father and proceeding with his consent is only the best course of action. Talk to your father and try to convince him by telling him all the reasons for your intentions in marrying that girl. Once he accepts and the family of the girl also accepts, you can go ahead and there will not be any problems.

As per the Hindu marriage act marriage in close relations governed by the definition of Sapinda relationships and are not legal within that. Counting from the present generation three generations back in the mother side and five generations in the fathers side come under the Sapinda relationship. So this is the legal angle and if someone marries in spite of this then if later there is a divorce or sharing of property or any other complication and some case is heard in the court then one of the party can bring this point that it was a Sapinda relation and was legally incorrect. That would create a twist in the case and couple would be harmed in some or more respect.
Let us come to another side which is not legal but is based on the human sentiments. If you are in love with that girl and feel that you are going to make a successful married life with that kind of girl and the girl also feels likewise then there is nothing wrong in going for such a relationship because you are sure that there would not be any dispute in the future between you and the girl.
Another important thing is that what is the view of your parents and her parents about this relation. Does everyone agree for it and there are no reservations? This is an important aspect because tomorrow you will have to live in that environment only and they would remind and curse both of you for going against their wishes.
The last thing that you both have to consider is that if your parents disown you and her parents also do the same then can you both survive in this world on your own. This is a question that one has to ask oneself and get an adequate and convincing answer. If you do not want any support from your parents and can leave your town and settle elsewhere then there is absolutely no problem as you would be taking a calculated decision in your life and being an adult person you have that right with you. Please go through all these aspects of your lives and then only take a decision.

Before you take the final decision of finalising this marriage, you will have to ensure the following points for achieving peace after your marriage and with your careful consideration of some the points as listed below, you would take up your decision in this sensitive issue -
1) First of think of the close relationship which applies to you and your would be partner if there is tge final settlement of the marriage and this relationship is known as Sapinda Relationship according to our Hindu Customs and such marriages within the Hindu Marriage Act is prohibited.
2) However, this relationship as stated above might not affect you couple at the later stage in case both of you would settle far away from your native places and there is none to criticise you and your couples due to no familiarity of your close relationship.
3) There is no objection either from your parental side or from your would be spouse's side.
4) Because of your close blood relationships, there is the possibility of genes defects of your off spring/ springs which might occur due to occurrence of the close relationships. Hence it is always better to ensure this vital point getting blood reports tested for both of you. If no abnormalities are found, you can think of proceeding ahead.
5) Both of you are emotionally attached and trust each other. There would not be any shortage of financial resources in raising your kids by the way of their educations, health and other needs.
6) Get the blessings of your seniors by inviting at least ten from each side and get your marriage registered in the court with the help of your lawyer.

At first, your relationship comes under the sapinda relationship. According to the Hindu marriage act, such kinds of marriages are not allowed. Another point is, that if marriage is done within a close relationship then there are chances to be born a baby with such a relationship that might get some complications. Besides, your parent's and her parent's approval is compulsory otherwise problems may arise in future. Especially, at the time of a property dispute and someone blames your relationship is illegal that time you will get deprived of property. As per my suggestion, you should convince your parents because without their parent's blessing you can't be happy. I noticed in my society, many people get married against their parents' will. But afterwards, They have to repent for that. Parents are parents they always want welfare for their parents. They do many sacrifices for their children. If you would need help in future they would support you. At a young age, physical attraction is common but don't ignore to parents' decision. And try to convince them. Every time money is not important sometimes a blessing is more important than money.