I need feedback from *MEN*

[RareTreasure]

I think my boyfriend is afraid of me dedicating my self for a lifetime to anything other than him, he has already lost someone else in the past to something he told them wasn't going to work out, tried it any way, then it didn't work out.
I tell him constantly it will work, but he just "Knows" that me joining a sorority will cause problems in our relationship. People say......."If he loves you, he will stick by you and hold you down," but as much as he is a dedicated, loyal person, the sorority is where he draws the line. He feels that if I do become a member of a sorority, I will not be the down to earth person I am because most people change. He feels that a sorority is not a necessity, its a want....so why cant I sacrifice a want for him. I don't see it that way.
What do I do? I have been researching this Sorority since I was a senior in High School, and not I am a senior in college.....I want to do it, but I cant loose the one person that's been there for me 100% of the time. I cant count on any one but him for anything...and I may loose that. Would I be being selfish it I did it? Would I be stupid because he is a very good person to me? I've tried to talk him out of it, but it never works. I've cried, and talked and he doesn't care about any of it. He just doesn't want me to do it and he feels that it shouldn't be a hard thing to sacrifice because I'm living fine without it now.
But what can i say to him to make him see that if he goes into this thinking like he is, he is going to make it not work. I tell him constantly.....i am an individual....and ultimately....i will do what i want to do. I just want him to realize that it is not as bad as he is making it. I need a male to tell me what they would suggest I tell him. I know coming at him in a harsh way and telling him "weather he likes it or not I'm doing it," will only make him mad, so I wonder what a man thinks will make him open up, calm down, and work with me.