You should not worry. Maybe he just hides his new girlfriend from you. Or he stopped trusting you. I understand you as a mother and I know how important parental control. I installed my daughter this mobile tracker https://www.hoverwatch.com
. It helps me to track her location, watch incoming and outgoing calls and track her activity in different social networks. I understand that this is not fair and wrong, but I do not want her to start using drugs or behave immorally.