Well, yes, this is quite specific, and definitely sexual.
There is a person, optimally a relatively older woman in position of at least some control, power or authority over one or both of the younger primary characters (be it parent or other relative of one or both, a teacher, chaperone, employer, landlord, doctor or whatever), who end up arranging, encouraging, up to directly (but not necessarily and preferably softly) forcing the younger couple to have sex between them, with or without directly participating in the act itself themselves.
While the "victims" of this process or event aren't exactly unwilling, and more than likely did hold at least nominal mutual sympathy beforehand (or at least from first sight if indeed perfect strangers), they won't have normally expected just that to happen. Ideally one or both are rather naive virgins not quite sure about anything. The premature consummation of their building relationship may or may not then become source of difficulty for it afterwards.
If the initiator is portrayed as actually conservative prude (at least most of the time publicly) who did it unwittingly just out of misunderstanding the underlying situation somehow, it's even better, but if she's just directly acting out of her own perversion or whatever personal (including sinister) motivations is completely acceptable (with a single possible contraindication of intentional, purposeful humiliation for humiliation sake; I'm not interested in humiliation of any kind, but can tolerate some of it if it's justified by realism or plot purposes).
Copious amounts of semi-public nudity are very welcome but optional.