Trouble in Bromsgrove

Why is David Cameron trying to hold onto Julie Kirkbride? The drip, drip of allegations has been fairly constant and it's said that 5,000 of her constituents have signed a petition asking her to go. But for me the simple and killer fact is that she is married to Andrew McKay and must surely take joint responsibility for the misdemeanours he has been punished for. They played the system together so if he was in the wrong so is she, morally at least. How does the marriage vow go again...?