Hi, I don't let my 19 year old bring his girlfriend (long term or over night) home for the night, and I get the same reaction. He has a younger brother, and the younger brother and I discussed wether we would feel comfortable with it or not, and decided not. If he doesn't like it, then hard luck. It's now a house rule. It may be old fashioned, but then a sense of morals comes from years and years of human behaviour! Good luck from me: @imabadmum