Aw, come on...give the guy a break. Maybe he turns into an ogre or something from 5 am to 6 am, so that's why he doesn't want you to spend the night. It's possible.
Equally possible is that he has an injured sparrow in his basement that he needs to take care of early in the morning and doesn't want you to find out because you might think he's a sensitive guy and lose the macho image he fights so hard to retain.
But, far more likely...I'll go with the scenario that he's got control issues and some other problem that won't let him commit to you.