"I know I said you wouldn't have to worry about anything, that I wouldn't interfere with your life." It had been the ideal, remain married on paper but not in practice. "I don't think that's realistic. I'm afraid that if there's no appearance of marriage, your mother might try to... divorce us."
It wasn't the true reason, but it was close. Shrouding his fears in May's words and May's presence at least made them palatable to them both.