My denial for what happened in episode 5 and 6 of season 2 of clone high goes as this:
WARNING SPOILERS
Before JFK and Harriet kissed in episode 5 Harriet told Joan she would be thinking of her when kissing JFK, and I just automatically assume that JFK thinks about Joan all the time because he’s absolutely smitten with her as we can see in the beginning of the series. So when they think they feel a connection to each other they are actually thinking about Joan instead and kissing her.
This gets help from episode 6 because when they make out with each other, not thinking about Joan, they feel absolutely NOTHING!! So obviously they both just want to kiss Joan and that’s it.