My partner has several items of clothing that him and ex have matching items T-shirts, shorts ect Embroidered or printed relating to various stages in their relationship / Wedding day. I have no issue with him keeping stuff like this. I understand it's a period in both of our lives you cannot just forget.
I myself have a wedding dress at my mothers as well as a couple of wedding gifts which are personalised but have chosen to keep there until I decide what to do.
When we moved in I put them all at the back of the wardrobe neatly when I sorted all our clothes and he questioned where they had gone, I said that where they were and why (I did it basically because I didn't expect him to want to wear them but he obviously does). I know all about the reasons behind them and the backstories he couldn't help telling me and it's made it worse for me when he wears them.
Aibu to politely ask him not to wear these things?