undies

Is it weird for guys to be smelling and messing around with my panties and bikini bottoms? I've caught my bf masterbating, jacking off smelling my panties a few times. I've also noticed that when his friends are over that they have gone through my hamper and messed around with them and taken them. I've also noticed when I hang my swimsuit up to dry, my bikini bottoms are not where I left them. I've lost 1 or 2 bottoms? Why do they do that? What are they doing with them?