Yea, and I'm not going to try to defend a husband that would repeatedly do such; but I do agree with "Ohioan" that this is not the same type of crime as a "rape."
Such behavior, between a married couple, really isn't in a standard "rape" category. And I'm not at all sure that our criminal statutes and enforcement mechanisms are appropriate for dealing with such things.
Don't invite the police into your bedroom unless your quite sure you want them there.
The notion that a person gives up all right to (or any portion of) the sanctity of herself simply because she is married is 12th century at best. No one owes another person sex. Period.