Instead, she hung up her love and her longing desire in this cloud of unknowing and she learned to love a thing that she might never see clearly in this life, neither by the light of understanding of her reason nor by a true feeling of sweet love in her affection. 
Clearly, the kind of love this author has in mind is of a fundamentally different quality than what we usually mean by love.
The love presented here is not affectivity or feeling, but describes what we would nowadays call nondual perception anchored in the heart. The heart’s energetic bandwidth is intimacy, the capacity to perceive things from the inside by coming into sympathetic resonance with them. In contrast to the mind, which perceives through differentiation (I am me, because I am not you), the heart takes its bearings directly from the whole (the “I” and the “you” drop out), through a process that scientists nowadays describe as “holographic resonance.”