I think your BF is probably a little afraid that you are expanding your horizons without him. To him that probably means that he is also concerned that you will meet new friends that may replace him. Men are a bit hard to read since they usually can't verbalize why they feel the way they do....too touchy feelie. Keep up the open discussion and perhaps he will see your point of view. Remember he feels a bit responsible for getting you into cycling and it is scary if you are moving in a direction he does not understand. When all is said and done, it is your bike. It took awhile for my DH to understand why I wanted a CX bike. Once I got it and he saw what I used it for, he bought one off of eBay last night. YMMV.

Good luck,
P2