I would be happy to help assist you in understanding your dream. Your dream can be symbolic of a few different things. The witch can be symbolic of evil, or negativity in one's life that is causing division. So this witch who has your GF locked in the house can be showing perhaps a "part of her" that maybe negative. Perhaps depression, certain negative thoughts or judgments towards others. It could relate to bad behavior or bad habits your GF maybe struggling with. Since your locked out it may give you the feeling your not able to help her. It can also be showing evil in one's life if you believe in demons and spirits and depending on your relationship regarding God. If you have anymore questions please feel free to ask.