Most to least likely to wear couple clothes/items:
Jaemin: He would be the one to buy them 😂. He would love showing you off and showing everyone that you were his. He would have no problem wearing a matching shirt or piece of jewelry because he found it cute!
Jisung: He would find it so cringey and embarrassing. "Only weird clingy couples do stuff like that". If it were something subtle like a ring or bracelet and you begged him then he might be able to do it for you because he loves you, but he would never be caught dead in any lovey dovey couple shirt!