I think the point Schnarch was trying to make is that people seek validation for other things besides "f*ckability" both when they seek and avoid sexual activity. The HD partner isn't dysfunctional because they perceive sexual desire from their partner as validation of their sexual desirability. The HD partner is dysfunctional when he/she seeks validation for things besides sexual desirability through sex or avoids seeking sex even though it is wanted in order to maintain a level of validation for other attributes. The LD partner is dysfunctional when he/she seeks validation for other attributes in order to be sexual.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver