Boyfriend With Orthopedic Back Troubles....

My boyfriend was in a sever motorcycle accident in 1991. He has a very hard time and many orthopedtic issues. He is on narcotic pain medication from his doctor and has been for almost a year now. Recently, i've noticed a difference in him and wanted some insight. He seems to be having some loss of memory. He loses a lot of thing and blames me for it. I have found some of his lost things, like items of clothing, mail, etc. He is also ending up with some of his pills missing and he had to take half his normal dosage towards the end of the past two month's prescriptions. I believe he is getting up and taking them in his sleep or is in so much pain, he is not realizing he is taking more than he should, awake or in his sleep. Is this possible? There is only two people in this household...Me and him. The pills can't be growing feet and walking away. He insists he is not taking more than his normal dosage per day. I've also noticed some differences in his behavior. Our relationship is rocky right now and he will escalate a disagreement, and yell and say horrible things to me. He insinuates that I am taking his pills on occassion, especially when he is really upset. He says he knows how many he has and how many he takes per day, so it has to be me. I am having a very, very hard time dealing with it. There have been days I wanted to leave to go check into a hotel for the night just to remove myself from the stress. Between the insinuations and the hurtful insults he says, I have a hard time feeling happy. I do everything I can to help him. I work more than full time hours and most all the shopping and cleaning at home. He is disabled and can't do as much, so I am happy to do it - but the hurt that I am harboring is killing me. I have my own set of health problems that stress is not helping. He has not been fully diagnosed, but he has some ms issues going on now also. Could any of his recent behavior and loss of memory be related to the long term use of the pain medicine. He is on 15 mg percocet three to four times a day. Most days, I believe he takes four. I need some advice because I love him and want him to get better. He never used to act this way. This has all started in the past few months. I hope that our relationship can be repaired and this problem with memory can be helped. Any advice would be greatly appreciated.