My iphone automatically deleted my conversation?

So i had a conversation with my friend that had been going on for months now. I woke
up this morning and checked for a message from him and THE ENTIRE CONVO WAS GONE. I don't know what happened. I honestly don't even know if he texted me know because the conversation is gone and i don't know when it was deleted. How could this have happened? Does iphone deleted messages for some reason? Or did i just do it in my sleep or something haha.

My friends do it