The very fact that OP's brother suggested a venue change shows how clueless he is about the wedding planning. The fiancé has every right to be mad not because it is her dream venue and her dreams are more important but because she seems to be the one doing all the planning and holding everything together. OP just unnecessarily created a divide in a relationship for an issue that could have been easily resolved without disturbing the peace of the couple..And OP's brother trying to move mountains to appease OP is not healthy. It's like OP is used to always getting his way while viewing themselves as having a very accomodating personality while OP's brother seems to be someone who earns for OP's approval and has been living under his shadow all the time.