i thought all teenage boys got a thing for friends mums at some point, i suppose step mum isnt much different. on the other hand he may be thinking about someone else entirely and just using your stuff cos thats what he can get his hands on, things arent always what they seem. if you have a good relationship with him i dont think i would risk spoiling it by saying anything. wouldnt change routine either cos he will proabably twig something is going on. sorry for laughing, didnt realise this was upsetting you.
HE knows I know - I went in and caught him fiddling with something under the covers and looking guilty. I asked what he had under there (with hindsight, probably a bit risky at his age)!!! I thought he was playing with his Gameboy. I told him to pull back the covers and he did and I saw this black thing and he threw it at me and said " I don't know what they're doing there).
I just picked them up and walked out.
I was in my bra at trousers at the time - have never had a problem with him seeing me in my bra - he watched me breast-feed so think nothing of it. Well, I will now.
i would probably feel uncomfortable walking round in underwear now this has happened, but stopping him touching your clothes is not going to make any difference to what he is thinking. maybe get dh to buy him a magazine?
Perhaps he's not doing it because he fancies you, but because he likes the feel of the material, or he can fantasise about someone else (not necessarily you) wearing them. He's a teenage boy, they're a mess of hormones and it sounds pretty normal to me. Don't make a big issue of it.
And walking into his bedroom wearing just a bra and trousers is probably not sensible anyway, if the truth be told.