I think they have a very good relationship but one that is a bit fragile in terms of fear from Park that Caroline is more free and adventurous, that he likes it being just him and her, but she likes to have fun and explore. I don't think for a moment Caroline is being sly to Park, just having some fun with a friend. I am sure Frisky has real feelings for her but yes, she doesn't want to cause any pain, though her passion is quite clear. But it is fascinating to watch and see the sexual tension coming from both of them.