I have been with my boyfriend for 3 months now. I stay over at his house one night every 2 weeks about. A few weeks ago I stayed over and had a shower and forgot to put my underwear back in my bag after. He texted later to say he found it and will put it in the wash with his clothes. Last weekend after shower he said my underwear is under a shirt in his wardrobe so got it and put it on. It looked very like mine and it was only when I got home I realised it wasn't mine. It was same size but the tag was cut off and different shape at back. I never cut tags off. Mine was also v new and this one was v worn(thong) I said it to him next day and said maybe it was his housemates and got mixed up in wash but he said definitely not. I said was it an ex girlfriend and said maybe..He just laughed it off. I feel a bit silly asking again but it's really bothering me. Does anyone else find this strange?