Every district has one. At least one. And the question must be, "Why is a place meant for dalliance declared in such an obvious way?" And the answer, of course, is that obviousness is the entirety of the point.
When manners and station will not allow impassioned words, such corners are places to be seen not being seen. Entering with a paramour is as much a declaration as singing out in joy, which one of good standing must never do. The alcove is thus a dignified means of announcing romantic affiliation, either for genuine partnership, or to appear as such in order to spare a suitor a refusal. Dignity of course requiring that one does not also make use of the darkness for actual physical gratification.
This has, of course, never occurred.