Should I get rid of letters from an ex to show my current partner I'm committed?

While I was sorting a box of old things, I put several cards from my ex beside university photos. My partner asked why I was keeping them. I said they belonged to a period of my life I didn't want to erase. He said, "I wouldn't need love letters from someone else if I was happy now."

I haven't spoken to that ex in years. The relationship ended, and I don't want it back. The cards remind me of the person I was then as much as the person who wrote them. They live in a box, not on display, and my partner saw them because we were sorting things together.

He hasn't ordered me to throw them out. He says it would reassure him if I chose to. That makes the choice harder: keeping them now feels like refusing something that would mean a lot to him.

Is there a way to take his discomfort seriously without making disposal the test of whether I love him?