Yekke: I would posit, as I believe Yankel does above, that if there is no justifiable cause for divorce (i.e. “being silly” as Sam put it), then it would be Bein Odom Lechaveiro for the spouse seeking a divorce without good reason to agree to remain married rather than the reverse.
Like Yankel pointed out, the spouse invested in his marriage the time, love, energy, a portion of his life and the joint bringing of children to the world. And a divorce is usually traumatic for both the spouses and their children and is a major life change for everyone. It is not only his legal right to insist but it is entirely fair that a spouse desires and seeks for shalom bayis and the continuation of their marriage especially if a divorce is being sought for silly or rectifiable reasons.