Dunstan yearns for Diana, why doesn’t he ask her to reconsider?

Dunstan felt that Diana would stand in the way of the type of life he wanted,

Why did I not find some other girl? Diana, Headmaster, Diana. I often yearned for her, but never to the point where I wrote to ask if we might not reconsider. I knew that Diana would stand in the way of the kind of life I wanted to live and that she would not be content with anything less than a full and, if possible, a controlling share in the life of any man she married. But that did not stop me, often and painfully, from wanting her.