Regarding the love problem in home girls parents not accepting

this is rahul....i am studying architecture....my age is 20 and my lover age is also 20 . our matter knows in both the houses. girls parents are not accepting us and they want to do marriage for her with another person. they are forcing her. we both want to study for 3 years and after 3 years we want to marry. but their parents were not listening. so, she wants to come with me. even if we were out of the house we will study for 3 years .after 3 years only we will marry. upto this time they need not force her. so, is there any legal way to take her from house. that i am not a major and the girl was a major . we have known that boys major is 21 whereas girls 18 only. so, please guide me one legal way to take her out from the family. because they are torchering her.