I've asked some local historians, they tell me this is just a Greek friend greeting, known as either the Platonic Tongue Lock or Sappho's Signature. They assure me there is no way these two are anything more than friends.
It makes me happy to see this, even in fosctional characters. I work in Sellwood sometimes, and the couples are so cute!
Saw a pair in La Paz BCS and a woman saw me smiling. I told her I would rather see a happy couple rather than an uneven power dynamic.