Hi Makeitreal and welcome to the forum. I just have a few questions..

- how old are u, ur bf and ur bro? I know age doesn't matter when it comes to love but there really are some who can't accept a big age gap..
- have you asked your brother why he doesn't like your current bf? Coz u would never know the real reasons unless u ask him..
- does he have a family of his own or is he still single? It's natural for a brother to care and be overly protective of his sister. but most people who already have relationships of their own would understand situations like this because they can imagine and put themselves in the same situation to understand it clearly..

These are just some points u need to know/consider in finding answers.. but u need to ask him his real problems towards ur bf so u can understand him and at the same time make compromises or solutions to it..