I dont think its a big problem as long as it doesnt cause harm. The main difference between an "unhealthy attraction" and a "kink" is that a kink is more like an "unusual attaction". Something csn be unusual without being unhealthy. The problem is if it becomes unhealthy. For me at least where cucking falls is pretty much on the line of unhealthy. Can you really have a healthy relationship that way? Idk doesnt seem so to me at least but then what is a healthy relationship even.