Ishmael caps off the story with a couple of conclusions he's come to about life and love. First, he has realized that "[t]he heart of any other, because it had a will, would remain forever mysterious" (32.81). Additionally, he concludes that "accident ruled every corner of the universe except the chambers of the human heart" (32.82).
So, apparently Ishmael has realized that everything that happens outside of yourself is basically luck of the draw; individual free will is the only thing that is not accidental. To make matters worse, this will is not something you can understand or know about another; in Ishmael's view, the heart of another human being is always going to be a mystery. Ishmael learned this the hard way; while there was a murder trial going on, he remained preoccupied with solving the mystery of Hatsue's heart—and failed miserably.
Although the ending might not give you the warm and fuzzies, it definitely reflects Ishmael's acceptance of the reality that surrounds him, which seems like a crucial step in his quest to get back to living in the present rather than basking in a cedar-shaded past. Also, it provides some hope that the human heart, when properly directed (like, perhaps toward justice?) can help combat the forces of pure accident and bad luck.