Tia,
I don't mean to sound negative here, but if I were you, I'd insist on this guy seeing a psychiatrist. This is FAR from a 'good relationship', and FAR from normal behavior. Not only is he delusional, he's paranoid and jealous, over NOTHING! Even if you are touching yourself, so what? It is natural. Why should you have to prove you are not doing something that is as natural as breathing? If he is so wrapped up in accusation and paranoid fantasies, he is going to cause you nothing but pain. He is jealous over you touching yourself, and that is an extreme form of insecurity. Granted, I'm not an expert on psychology, but I was married to a replica of this person. Most likely, he'll find other things to accuse you of, then use those things to justify beating you or to justify mental abuse. Make him get help, and if he won't, get out!! Have him get checked for bipolar disorder. This is terribly unhealthy, and it sounds like a time bomb waiting to explode. The problem here is not yours, but his (unless, of course, you LIKE being being accused of imaginary slights, in which case, examine your self-esteem closely!). You have the right to touch yourself, and if he is so insecure over that, you need to seriously look at just why you are with him. Make sure your self-esteem is not taking a beating here. Why would you allow someone to tell you whether or not it is OK to touch yourself? That's just wrong. The whole thing screams dysfunctional to me. Good luck, you are going to need it.