This story is a sequel to my fanfictions "Son of Ilúvatar" and "Daughter of Sorrow, Daughter of Hope" and cannot be understood without knowing the content of those two fanfictions. So let me give you a
summary of „Son of Ilúvatar":
After his death, Boromir reaches Valinor, the blessed island in the West, eternal home of the elves and resting place for the souls of the dead. There he meets Galathorn, who turns out to be the person known in our world as Jesus. Having glimpsed a vision of him on the cross, and wanting to understand further, Boromir is transported into our world. Here he meets a young woman whom he calls Ninglor. She introduces him to her world and he forms a tentative attachment with her before he is abruptly taken back to Valinor. Having fallen in love with Ninglor, he yearns to return to our earth to help her with her problems, but he has to deal with his own issues first. Having received forgiveness for his mistakes and inner healing, having given his life to Galathorn and dealt with some of his past demons, he is offered the choice to either remain in Valinor, return to our world, or return to Middle Earth alive once more and continue in the fight against Sauron. Out of love for Ninglor he forfeits his beloved Gondor in favour of our world, even though he has no guarantee that he will find Ninglor here or that his love will be accepted by her.
summary of "Daughter of Sorrow, Daughter of Hope":
Having returned to our world for Ninglor's sake, Boromir tries in vain to find her. Bitter, desperate and estranged from Galathorn, he finally lights upon her lying in the snow after a suicide attempt, apparently dead. Grief-stricken he lies down by her side after some vain attempts of reviving her, ready to die with her rather than leave her. But Galathorn intervenes and saves her life. As she awakens in Boromir's arms, he vows never to leave her.