If I come across items of my exes (which is rare because we haven’t been together in years) I just ask if he wants them back. If he says no, then I do whatever I see fit with them (keep, donate, trash).

Perhaps a clean out is in order? Typically it happens after the big breakup but understandably not always. It can be cathartic to get of constant reminders of your past relationship.

If you decide to go that route, a storage bin or two (or more depending on how much stuff we’re talking here) would suffice. You can just tell him you did a clean out and found his things and are returning them and do so the next time you see him. Whatever he chooses to do with everything is then up to him.