Personally I would have no problem in marrying an astrologer. Though it is a lot less developed than other branches of knowledge, astrology studies a property of the Creation, namely the influence of planets and star on nature and men. However due to my religious beliefs I cannot marry those who practice occultism, magic, wicca, etc.
The problem would not be me considering to marry an occultist, but an occultist wanting to marry me!
Depends on what you're looking for in a marriage, I think. Communication and sharing of ideas/beliefs is not so important in all cases. If it is, however, having a common ground for communication is very helpful, especially when it comes to sensitive subjects such as spirituality/religion/personal beliefs.