Want to do Love marriage with my girlfriend without hurting my family and her family.

I'm 20 years old, and I love my girlfriend so much, and I also love my family, but the problem is that she is the daughter of my father's sister's sister in law(buwa ki jethani), i want to marry her in future but tension comes with me all the time how to get married with her, so please help me how do i get married with her without any problem because i know there are chances of family problems in future so how to get rid of this help me suggests me.