In `Style is Matter' Leland de la Durantaye asks what "gargoyle" Nabokov could be exiling in Lolita, and plausibly suggests that its the temptation to "solipsistically" interest yourself in your own an artistic vision or experience of a loved person rather than that person themselves. I want to tentatively suggest that Nabokov's description of Humbert's experience during the couch scene – functions to parody or suggest possible dangers of (or at least draw attention and comparison with), the odd approach to romantic relationships advocated by ``That other internal combustion martyr" (as Humbert calls him) Marcel Proust.
In the couch scene Humbert directs his attention, for the purposes of furtive masturbation, away from the girl Lolita towards something like his experience of her. He focuses on, not the real Lolita but "[his] own creation, another, fanciful Lolita – perhaps more real than Lolita; overlapping, encasing her; floating between me and her, and having no will, no consciousness—indeed, no life of her own" whom "nothing prevented [him] from repeating a performance that affected her as little as if she were a photographic image rippling upon a screen and I a humble hunchback abusing myself in the dark."
Now, this method of shifting your interest from a person to your experience of thinking about that person which (de la Durantaye argues) gets Humbert into trouble, seems very similar to the unusual response to romantic attraction which Marcel appears to advocate in Remembrance of Things Past. For example, in the following typical passage Marcel reproaches himself for a surprising form of laziness – interesting himself in a beautiful girl selling milk, rather than investigating and artistically reproducing his own experience of seeing the beautiful girl with the milk – in the passage that follows:
``That handsome girl whom I still could see, while the train gathered speed, was like part of a life other than the life that I knew, separated from it by a clear boundary, in which the sensations that things produced in me were no longer the same, from which to return now to my old life would be almost suicide. To procure myself the pleasure of feeling that I had at least an attachment to this new life, it would suffice that I should live near enough to the little station to be able to come to it every morning for a cup of coffee from the girl. But alas, she must be for ever absent from the other life towards which I was being borne with ever increasing swiftness, a life to the prospect of which I resigned myself only by weaving plans that would enable me to take the same train again some day and to stop at the same station, a project which would have the further advantage of providing with subject matter the selfish, active, practical, mechanical, indolent, centrifugal tendency which is that of the human mind; for our mind turns readily aside from the effort which is required if it is to analyze in itself, in a general and disinterested manner, a pleasant impression which we have received. And as, on the other hand, we wish to continue to think of that impression, the mind prefers to imagine it in the future tense, which while it gives us no clue as to the real nature of the thing, saves us the trouble of recreating it in our own consciousness and allows us to hope that we may receive it afresh from without.''
As further evidence for the connection between the couch scene and this aspect of Proust, I would like to cite a) the fact that Proust is constantly mentioned in Lolita more generally, and b) the close connection between Cartesian doubt and solipsism (which is mentioned in at least three ways in the couch scene in Lolita) on the one hand and phenomenology (which is a big theme in Remembrance of Things Past) on the other. One of the original motivations for doing phenomenology (i.e. studying ones experiences) was `methodological solipsism' – the idea that you would "bracket" the doubtable objects in the external world, and instead concern yourself with your experiences, which could be known with cartesian certainty and hence formed a suitable starting point for foundational philosophy.