Truthfully, he's the only one who can answer the questions you have as to why he's suddenly changed his viewpoint on marriage. You don't say how long it's been since his views have changed, or if you were supporting him prior to him getting this job. Unfortunately, sometimes people will agree to what you want to do and tell you what you want to hear when you are in a position to help them. Once they're able to handle things on their own, their true colors come out. Other factors that may influence his thoughts are new people he may be hanging around with, or maybe something negative happened to a friend that was married that he hasn't shared with you.

What's really important here is what you want. Can you be happy if he sticks to this point of view and never marries you? If the answer is no, then it may very well be time to sit down and have a conversation to get to the root of why his views have changed and what this means for the two of you. Make your decision from there.

Best wishes to you.