Advice please - Am I being unreasonable?

I love my boyfriend very much and weve been together for 8 years in a semi-long distance relationship (2 hours by train, but we see each other every weekend). Recently we decided that we would start looking to find a place together, either somewhere in the UK or abroad and he has just been offered a really good job in the Middle East. The problem is that I don't want to go there. This is for a number of reasons - firstly we would need to get married (down the registry office sometime in the next few weeks) as its illegal for us to cohabit there, secondly I am a little doubtful what job opportunities there are for me there (although I could probably find something, it might not be the best career move for me) and finally, I am terrified of medical stuff and in order to get a visa you have to have a medical exam. I have told him that if he goes then I cant stay with him (he worked there for 6 months a couple of years ago and it broke my heart). For him, this is a great opportunity and i feel so awful for saying i wont go. I've said that if he stays in the UK then i will move to be with him, or we can move to a mutually agreeable country together. But Am I being unreasonable...?