Greek life interfering with relationships

[soon-to-be]

I'm currently an interest/prospect for a sorority at my school. I know that I will soon be beginning my educational process and I'm worried about it affecting my relationship with my boyfriend. He has made it very clear that he does not like the greek system and that he does not approve of me pledging/joining a sorority. I have tried several times to discuss it with him and reach some sort of compromise and he usually shrugs it off. He's not threatening to break up or anything but he's not exactly being supportive either. I know that in these following months my time with him will be limited and I'm worried because I know he might be resentful. He doesn't understand my reasons for wanting to join a greek organization and he doesn't understand the purpose for a pledging process. I've tried to explain it to him but he gets insulted and doesn't understand that I am limited to the information that I can share with him because we've never kept anything from each other before.
I need advice on how I can maintain a good relationship with him and how I can get him to be more accepting of my decision. I've been with this guy for a long time and I love him...I don't want this to tear us apart. I would appreciate any advice that you guys have. Thanks.