A perfectly respectable romance archetype! Think Tauriel and Kili or Mizuki and Caius. In both cases, the archetypes work in part because the issue is less about size or height and more about culture.
But a romantic relationship between a miniature person and a human is always, ultimately, about the difference in height.
In my fan fiction, I had one of the Littles, Tom, meet a human. Much like Arrietty who continually seeks out humans, Tom wants to make contact beyond his somewhat limited family circle. And he becomes attached. He takes himself off to the same college as the human, where he makes a home for himself in the area behind the brick facade above a dormitory window, and--
I then realized that for the relationship to move forward, I would have to resort to "science" (a la Honey, I Shrunk the Kids) or magic or dreams (a la Alice in Wonderland).
That is, I was not trying to establish a platonic friendship or even a platonic chivalrous admiration but, rather, a romantic relationship with the attendant physical relationship. And unless it descended into salaciousness (see Gulliver's Travels), it needed to be on an equal footing in both the literal and metaphorical meaning of that term.
"Equal footing" can cover a lot of territory. Note Tauriel & Kili, Mizuki & Caius above. "Short" or technically little (LP) and "tall" or technically average-sized. Or someone in a wheelchair and someone who is not. All these relationships can work!
Miniature and fully human, however, gets into the metaphysical.