It seems that you really care for him, and you could see yourself wanting to marry him. Its a good sign (:

No, but that does mean that he doesnt trust you, he must feel insecure. And you shouldnt be accused, thats not right.

You can tell if things arent the same as they once used to be. If you don't want it to fall apart then let your bf/gf know that.

That just shows that he cares, and he wants you all to himself because he can't picture you with any guy but him. Its completely normal for him to get jealous. Just simply talk about it with your boyfriend and calmly let him know that there is nothing to be concerned about.