These feelings can arise if your boyfriend has been paying you less attention than usual. An alternative interpretation is that you're feeling vulnerable and your self-esteem is low: Perhaps you're worried that you don't measure up to his ideals or expectations. You may find that you are lacking in trust and self esteem.
Does This Mean My Boyfriend Is Cheating On Me? Probably not! You might just be worried of losing him. This is perfectly normal, and doesn't mean you're paranoid or anything. It's best not to act on dreams like this - I definitely don't think you should accuse him of cheating!
However, our minds are mysterious, and we don't always understand what we feel or think until our subconscious shows us what is going on. Maybe you do have reason to suspect that your boyfriend is really cheating on you, or is not committed to the relationship.
If you believe in dream interpretation, then you'll need to consider your feelings before looking for alternative interpretations. Your boyfriend may be distant because you are - he may be holding back because he senses you do not need him, or that you are not being as truthful about your feelings as you should be.
If you are really worried about being cheated on by your boyfriend, then ask him how he feels. Tell him that you had a dream where he cheated on you, and tell him how it made you feel. Put your feelings out there to show him you are committed!
For a fair and equal relationship, you have to be willing to open up to another, in order to expect the same in return.