When Kagome first notices that her injuries heal faster than they should, she rejoices: No longer will she be incapacitated by even the smallest wounds. Then she learns better, lying in a pool of her own blood and watching as her body reassembles itself like the youkai using the shards of the Shikon jewel.
When Inuyasha leaves with Kikyou and Kagome feels her soul returned after discovering that the well has closed, she learns about many kinds of pain: Cutting her wrists as the skin closes behind the blade. A dagger in the heart grows on and has to be wrenched out, ripping her insides. Throwing herself into fire where the skin burned heals instantly, continuing pain. Trying to drown only to learn that she needs no air. Trying to starve only to find out that she needs no nourishment. But the most excruciating is poison that lingers in the body for weeks causing phantom pains. But none of these can be compared to the ache of a broken heart.
At some time during Kagome's ordeal Sesshoumaru appears, surprisingly apparently trying to soothe the overly worried Sango and Miroku: "She will get over it." And so she does.
Kagome settles down as a wandering miko, sometimes visiting the newly begun slayer's village to be introduced to the newest niece or nephew.
And finally on such a visit, she has to admit to herself the most agonizing detail of her unknown powers. "Auntie Kagome looks always the same! How old do you think she is?"
"I don't know, but she looks younger than our oldest sister. And she's so pretty. When do you think she'll get married?"
"Don't be silly, she's a miko! Miko don't get married."
Kagome is healed of all things: of injury, of sickness, of age, of death. She is truly immortal.
When Sango and Miroku die peacefully of old age, Kagome stops visiting. She settles down in a village, becoming a common village priestess.
A miko, a village girl, a farmer's wife, a slave, a geisha, a lord's wife. All of these she has to abandon after a few years because she doesn't age. All men she is married to are disappointed to find out she is barren.
Disguised as a youkai she fares a little better, but always Sesshoumaru comes and says: "Come away, you're not meant for this." And so she follows him for a few seasons until she tries again.
After two and half centuries, she begins to wonder: "Sesshoumaru, even youkai age, but you do not." Sesshoumaru doesn't give an answer bur Kagome finds some relief in his permanence.
And the truth is revealed according to her speculation. "Cease this foolishness. You are not the only one suffering of this curse." Sesshoumaru is almost seven centuries old so he does know better.
When Kagome is born Kagome is present. When she falls into the well Kagome is present, taking comfort in the past. When Kagome visits home for the last time Kagome sits in the Goshinboku, Sesshoumaru holding her up as she weeps.
As soon as Kagome disappears down the well for the final time, Kagome races to hug her mother.
When Kagome's mother is introduced to Sesshoumaru, Kagome is surprised by her reaction: "so you have found a husband!" Kagome blushingly denies the presumption. "He is only my companion in fate. He suffers of the same curse I do." Sesshoumaru in turn is taken to his thoughts.
Decades later when Sesshoumaru first asks Kagome to marry him, Kagome thinks he is joking. But he isn't: "You are the only one who can stay with me for my eternity. I will need a wife for the sake of appearances as do you a husband. I have no wish to go through the same procedures for courting, wedding, convincing her that we will not be having children, either divorce or her illnesses and death at least every sixty years also falsifying my aging. Our marriage will be a farce, should you wish it, but I do not see any obstruction for our marriage to be true and lasting."
Kagome considers this for a good time and then gives her consenting answer. And so they are married, Souta, now a grandfather himself, accompanies the radiant Kagome to Sesshoumaru.
Years later, when they finally consummate their marriage, Kagome sighs: "So this was missing."
And as the centuries roll on they adjust for they can do nothing else. They have an eternity together. Nothing else.