Thanks for all the support/advice everyone. I don't think there is a hidden issue or anything. I think his mom just sees Mexico as a dirty, dangerous place and his dad does whatever his mom wants. We are getting married legally in the US before our DW and they have said they want to come to the courthouse with us. They do seem to support our marriage- just not our choice of location. And like many of you have said- they will regret it in the end, but we won't regret having the wedding we really want just because of them. My FI and I are actually at a good place with it now because with his Mom comes drama and it will be nice not to have that at our wedding.