CFNM (clothed female, nude male) and CMNF (clothed male, nude female) are about purposefully asymmetric nudity. One of you is nude and the other is not. It’s closely related to dom/sub, although you can actually make a case either way as to who is dominant and who is submissive, the clothed one or the nude one. It’s possible natural personalities will lead to the dom and sub roles more than the clothed/nude status, for example.
Nudity is tons of fun already, but having an imbalance between a couple, where one is nude and the other is clothed, can add a new dimension to it. If the clothed one is the dominant one, I recommend using that to sexually harass and molest the nude one at every turn. If the nude one is more dominant, I recommend teasing and tempting the clothed one at every turn. Either way, masturbation as a show is a common part of the experience. Playing with the cum, of course, adds more fun.
You could turn it into a challenging game to tempt the clothed one to disrobe and join you. Or the clothed one could try to force the nude one to orgasm while the nude one tries to resist. At the extreme end, humiliation of the nude one may be involved and in front of other clothed friends. I’m not into humiliation, but the social aspect of it could be fun and even empowering (for all parties).
CFNM/CMNF can be lots of fun if you keep it edifying for both. There are multiple dimensions you can explore and enjoy together. Even if it’s the dom/sub aspect that moves you, remember it’s about the sex!