I think the producers can set up everything so it's filmed to their liking e.g one 'goodbye' filmed with meg & Wes in the foreground and one with G and Jack in the foreground as that's just generally how tv works. E.g the first shot was of Meg and Wes in the foreground and G and Jack are preparing to say bye but no kiss as its not their 'turn' yet. Second shot is G and Jack kissing (whether spur of the moment or instructed) and Meg and Wes in the background, where they've also decided to kiss again.
The producers can instruct them to kiss for 'drama' but the contestants are adults and can choose whether to hug, kiss on cheek, or kiss on the lips.