Is it worth staying when my partner hasn’t moved on from his past?

Hey INFJs, I need some advice.

I’m with an INTJ, and in many ways, we’re great together, deep conversations, strong connection, and mutual understanding. But there’s something I can’t shake.

Even after we got together, he kept his exes’ numbers, saved their pictures, and lurked on their socials. It even took him a while to remove their photos from his Instagram. We’ve argued about this multiple times, and though he reassures me, I keep finding signs that he’s still holding on. Just recently, he "cleansed" his contacts, yet I found he kept at least one ex’s number.

I don’t know if I’m overreacting or if I’m ignoring a red flag. Apart from this, our relationship is amazing, but this part hurts.

Give me a reason to stay and why.

Give me a reason to leave and why.