my facebook chat history with a particular person is gone?

[chocolateapple]

i had a long chat history with this particular person, but now it doesn't even show up in my inbox?
we aren't facebook friends, but he didn't block me (i can see still search his name up in the search bar and it gives me an option to add as friend)

can someone offer an explanation? chat history doesn't go and disappear does it?!
if he deleted the history, would it have deleted from my inbox as well?

Thanks!
i swear i didn't delete it ): sigh