Udelhunny, I think that you just have to be open and honest w/ your boyfriend. Just let him know that this is something that you want to do and that it would mean a lot to you if he supported you through it. In my situation, not only was I in the process of joining a sorority, but I was chartering a chapter of my sorority on my campus. So I had to make an even bigger commitment than most others that join a chapter already established. My boyfriend at the time honestly thought sororities were stupid. He didn't see the point of going through all the "hoops" to get in a group that you call "sisters". He obviously was NOT educated on greek life like myself. But, once he saw how serious I was about it, he backed off and eventually began asking me how the process was going or if there was anything he could do for me.
So I think you just gotta show your bf that you are serious about joining a sorority and I'm sure that he'll support you through it. He might not like it at first, but that may be due to his lack of knowledge about greek life. If he's against it, he may just be thinking of all the stereotypes that are involved. Just assure him that those things
rarely are true and that joining a sorority will be a great benefit to you and your college experience. It's funny but sometimes guys need a little assurance too just like us
Good luck and I hope everything works out w/ you and your bf!