Making Out scenes are unconditionally perverse on TV, regardless of age, except when used in order to parodise the perversity of mankind as a whole.
Quinn is a nerd, while Logan is a jock. Thus thye need to deprecate each other rigorously at any cost, no matter what.
For the same reason, hylic Fredward is not worthy of psychic Carlotta.
Carly is just a cozy form of Carlotta, as already figured by Samantha Puckett.