In Coelho's The Alchemist, the author's message regarding love is two-fold. About love in general, the reader learns that it is the one constant in the world. When the desert asks Santiago to describe what love is, the theme of constancy is present in his answer. Love is what links the falcon to man and man to the desert. Love is in all things of the world. Even the sun remains distant from the world it loves so as not to cause it harm. Love is everywhere.
With regard specifically to Fatima, Coelho seems to be saying that those who love you will not get in your way or try to hold you back. They will wait patiently as you follow the path that enables you to realize your dreams. The alchemist (speaking of Fatima) tells Santiago:
Love never keeps a man from pursuing his personal legend. If he abandons that pursuit, it's because it wasn't true love.
It is important to note that Santiago is devoted to Fatima, but believes he must also pursue his Personal Legend. He does not ask her to wait while he meets other women or travels around the world for fun. His purpose is clear. His commitment to her is unshakeable.
And Fatima's faith in Santiago enables her to let him go, to do what he must without feeling guilty. She does not try to make him stay. She seems to be as certain of him as he is of what he must do to be happy.
“The dunes are changed by the wind, but the desert never changes. That’s the way it will be with our love for each other. Maktub,” she said. “If I am really a part of your dream, you’ll come back one day.
Fatima understands that there is room enough in Santiago's life for the pursuit of his dreams and his love for her. She believes that they were meant to be together, he will surely return. She notes that she is a woman of the desert and that men leave all the time in pursuit of what they must do, while the women stay at the oasis and wait for their men to return.
She would have to send her kisses on the wind, hoping that the wind would touch the boy's face, and would tell him that...she was waiting for him, a woman awaiting a courageous man in search of his treasure.
Santiago knows as soon as he sees Fatima that she is the one for him. Love, as it is presented here, comes to the heart, not to the mind. Santiago recognizes his love simply by being in Fatima's presence:
What the boy felt at that moment was that he was in the presence of the only woman in his life, and that, with no need for words, she recognized the same thing. He was more certain of it than anything in the world.
Santiago feels the hand of destiny in finding Fatima, just as she does:
...everything under the sun is written by one hand only. It is the hand that evokes love, and creates a twin soul for every person in the world.
He devotes himself to finishing his quest and returning for Fatima. The very end of the book supports this as he discovers the treasure at the bottom of the tree at the church, back in his homeland—though he acknowledges that his greatest treasure is not gold.
The wind brings her perfume to him, and a kiss. As if fulfilling his promise to her, he whispers:
I'm coming Fatima.