Exploited: The Handsome Lech is assigned to greet the ambassador in order to improve diplomatic relations. Or just keep the two of them out of the way for a while.
Defied: Meteora (or Bob, or both) has reservations about having sex with a stranger (especially one of a different species) and/or is already Happily Married back home. Both of them have a conversation and agree not to pursue any desires they have.
Discussed: Bob and Meteora talk with each other about their relationship.
Conversed: Alice and Bob talk about two differently specied characters' relationship from the Show Within a Show.
Bob and Meteora could give each other all kinds of nasty sexually transmitted diseases (or even diseases in general) that neither species is used to, causing its demise. And there might be some...mechanical issues, depending on Meteora's Bizarre Alien Biology. Also, they could be seen as traitors to their species, and who said this sex was necessarily even consensual?
Because they're different species, Bob and Meteora's relationship is considered the equivalent of zoophilia, and are treated as freaks by the public.
Reconstructed: Bob and Meteora either control their sexual urges, or take precautions (i.e. Bob wears a condom) when acting on them.