I don't think we even know whether they are or consider themselves lovers, or are just flirting for now
it doesn't necessarily matter either though; the "Veil" to me seems like the subtle friction between their "different worlds". "Her sense of intimacy is different from others" and "he consistently looks at the purity of his attitude" - while she seems eager for a tactile connection, he seems to be to a bit worried about not treating her right with her lack of sight. Yet the "tickle" of the veil is not necessarily uncomfortable either, as we see in their interactions
This sense of tender cautiousness and perhaps curiosity in their flirtation is also what to me sets it apart in "temperature" from a fiery blaze of passion or a platonic affection
maybe I didn't make any better sense of it, but that's my thoughts anyhow