Kierkegaardian view of romantic love makes love not be based on a quality of the beloved such as her generosity, beauty, intelligence, chastity, plenitude of jewelry or knobbiness of knee. A love grounded on these kinds of qualities would not really do justice to the irreplaceability of the beloved, the mysterious incommunicability of the beloved.
But what does Kierkegaard put in the place of such qualities? It is a choice by the lover, a choice to love. But then on Kierkegaard's view, romantic love is, after all, based on a quality, a quality even more fickle than beauty or plenitude of jewelry: the lover's choice. And this, surely, is even more problematic, shifting as it does the focus from the beloved to the lover.
I think this whole business of finding reasons for love is silly. For we always have decisive reason to love another person... just because the other is a person. The question is not of what reasons we have for loving, but of what reasons we have for loving in a particular way (friendly, filial, romantic, etc.) And this question is both less momentous and easier.