Boyfriend has nightmares? what should i do?

Be gentle with him: Be gentle with him if he's waking up at night with these -- and cautious if he's agitated and flailing in bed. Encourage him to get help if these are recurrent, as it sounds like they are. Nightmares can result from traumatic experiences being relived and released in sleep. He may need evaluation and help for their source. This is available through psychiatrists, psychologists, and others.