Does it? I suppose, of course, it depends on what one means by “duality”; but commonly speaking, the word “love” means some quality of affection, consideration, or care.
Of course, when the word “love” is used in the context of people involved in a sexual relationship, it usually means desire and attachment - but even then, some quality of affection or consideration is still assumed.
Within families, the word “love” can mean responsibility, attachment, duty or fidelity - but again, some quality of affection or care is assumed.
What I understand K to be saying is something very simple: namely that we limit this quality of love to a only few accepted forms of relationship, and in so doing also limit the quality of love itself.
Love itself may not depend upon or require any exclusive relationship with another - it may simply be part of the nature of attention, of a mind that is sensitive, awake to the world (a sensitivity in which there is no division, no sense of separation, etc).
But the quality of love - as affection, as care - is not something an ordinary person has no sense of at all. This quality is necessary to look at a tree, a bird, a flower; to listen to what another person is saying. So I think it is a misunderstanding of K to assume that he could have used any word at all and that the word itself conveys nothing meaningful.
As the Japanese writer Murakami said:
“If you can’t understand it without an explanation, you can’t understand it with an explanation.”