They are demonic and he is trying to form a bond and make covenant with you. Sexual dreams are never good. Never.
You need to break covenant with this spirit. If you are single you will always be single. If you are married it will ruin your marriage. This is what you call a spirit husband, and who wants to be married to a demon? Remember, sex is only OK in the covenant of marriage. Rebuke it, break ties with it as soon as you read this.
The next time you have these dreams you need to rebuke it immediately denounce it and tell those spirits you are not in covenant with them and never will be. Cut ties.