A similar pin from the Louvre was exhibited in the Metropolitan Museum’s Art of the First Cities exhibition in 2003 (no. 228). The catalogue entry records that while Pierre Amiet believes the couple are engaged in flirtatious banter, Victor Sarianidi thinks that it represents the transmission of a ‘revelation’ from one individual to another. Not that one precludes the other, in my opinion. The Louvre version only shows the couple beneath a curved lintel, while this example has an elaborate surround: a phallic symbol between recumbent lions below; a wriggling serpent up each side; and a balcony above the lintel.
Resolving the Amiet/Sarianidi difference of opinion is tricky. Human beings have not changed much over recent millennia, and therefore looking at modern fashion and whether it is promoting flirtatious icons, or deep meaning-of-the universe symbols, might provide a clue as to what is going on between this couple. Since this is a fashion accessory.