In this way that reward-oriented signals appear to generalize across categories, interest in doing something potentially entirely non-sexual with someone can end up feeling like an appetitive sexual attraction. Dipping into Freudian terminology again (this may seem quite basic for those steeped in psychoanalysis), this may reflect, particularly in the bookish, a regression to -- or sticking in -- the latency stage, in which appetitive drives are organized around the gratification derived from friendly and educational activities, the locus of thinking. Since many bookish people in fact make their livelihoods through the activities of thinking, it's somewhat amusing to note the ways in which sexualized appetites might be, in some lights, more culturally acceptable (more sexy, surely) than admitting to the pleasures derived from thinking with someone.
But it is not merely a matter of social acceptability and appearances; it's the experience of this reverse sublimation that seems fascinating: sexual tension is often the bond that holds much more prosaic associations together, and that simultaneously appears to provide some of the motivating sparkle and also to fluster people (according, no doubt -- if we continue to follow the Freudian line of thought -- to how honestly they're acknowledging and managing to work through defense mechanisms).
We creative bookish types appear to seek sensitization to these affordances to out our implicit desires: this is our habitual sublimating relationship with muses. What is more motivating toward an afternoon of creative production in the face of all other demands, than the challenges raised by unexpected desire? Non-compulsory challenges that fall outside the obligation of established relationships -- that we are nominally free to ignore, and yet that promise unpredictable consequences -- can be utterly galvanizing, particularly when these challenges entice us to consider goals that have been articulated perhaps not quite explicitly enough, or towards which one doesn't quite know how to progress or act adequately.
Many of us appear to cultivate a discerning eye for opportunities to be drawn in lustily by consuming desire -- for what often turns out to be not someone else, and often not even someone else's ideas (although it seems we often think of our infatuations as being with someone else or their ideas), but perhaps, more accurately, with the ideas they make us think -- or, more fairly, perhaps, think with us. We engage, in other words, with a (to-some-degree) limited (and potentially only partly intentional) heartsickness in order to think through thoughts that need -- not an audience for itself, but the emotional and cognitive stimulation a compelling (even if imagined, in the relational details) audience affords.
For the description of sublimation as process of transforming libido into "socially useful" achievements, see Carole Wade and Carol Tavris, 1996. Psychology. HarperCollins.