I m having frndsp with girl for 6 yr,initially wasnt intrsted but after her marriage fixation i m puzzled hlp

for the last 6 yrs i was nt interested but she told me 15 days ago that she is going to get married. after that i m thinking about her. is it love ? i m in govt. job n she is doing private job. she is not as smart as me both carrierwise as well as in look. we cannt get married because she is from my nearby village n according to rules of society she is my sister. chances of. families to accept accept the relation are 40 %. bcs of society. .We didnt had in last 6 yrs.both families know each other very well.i m puzzled whether i will be happy with her or not for whole life. i think she could be a problem in my carrier also. i m in final yr n wanna prepare for CAT or some good job. i fear my friends will say is this ur choice bcs he is not much smart .the only one thing favouring her is that i know no girl on this planet can love me more than her. is it love?should we marry ?she is ready to marry but both we dont want to run .age-(22,21.).plz give me practical solution