Hi, I'd like to help you with your question.
Whenever someone develops a sudden fear, it is usually due to either a recent trauma of some sort or a significant change in the person's life. In your case, your move into your boyfriend's home probably triggered your fear reaction.
Since you are afraid of the paranormal and do not experience fear during the day or in any other situation, you don't necessarily have a phobia. What may have occurred is a transfer of feelings from one thing to another. What I mean is that you may have been more unsettled by the move into your boyfriend's place than you realized. You may have not recognized how you felt right away and instead transferred your feelings to the fear you have at night.
People fear change for many reasons, often not consciously. The mind has to find a way to cope so it expresses your fear in other ways. That is why phobias seem so unrealistic.
What you can do is examine your feelings around your recent move. Did you feel upset about giving up your place, maybe more than you thought? Or did you and your boyfriend have any conflicts or unresolved issues before or during your move? This may have made you question your move, even in the back of your mind. Once you can pinpoint what feelings may be causing this and you deal with them, you should begin to feel better.
Also, you may want to try talking to others about your experience. By sharing how you feel with trusted friends and family, you can unburden yourself and find support.
If you attend church, you can also speak with your pastor. They can not only offer support and comfort, they can address the nature of your fear.
If you find that you cannot work out your feelings, you may want to consider some short term counseling just to figure out why you feel this way.
I hope this has helped you,