Things he won’t throw away

If your boyfriend has things from someone he was talking to and hasn’t thrown them away even after you’ve told him several times it upsets you, what would you do. And those things are around like in his car ...

For the comment under “L”:

These are things he was given after breaking up with me, he didn’t get in a relationship but was talking to some other girl, then he and I got back together. So they weren’t a thing.