The following can be conceived as a commentary on Lacan's statement that love comes to supplement the lack of sexual rapport.
Formally, one must determine what a function of supplement is, even up to the point at which a rapport cannot be written. Ontologically, one accepts that if sexual rapport cannot be written, if it is non-existent as an effect of structure, then love itself as supplement can only arrive by chance. The event that must be registered as love is what, in my language, establishes that the sexual is of the order of being. It is what Lacan asserted when he professed that love is an approach, or a "coming aboard": "Being is love which comes aboard in the encounter."
The encounter is, in effect, the name of the amorous chance, inasmuch as it initiates the supplement. It is, of course, the encounter guided by the obscure star of the object, but in excess of it, since it goes straight to that aspect of the object from which the subject draws its little bit of being. And, through a reversal contained completely in the declaration "I love you" (it's you I love, and not exclusively the object you carry), love comes to assert — this is its constituent excess — that it is from the being of the subject that the object, as cause of desire, has the singularity of its presentation, and finally the charm of its appearance.
In comparison with the essentially disjunctive sexual difference, love, in subsuming the object under the being of the subject, constructs the introductory scene in which the non-rapport takes place as counting, the counting-for-two.
As a consequence of an encounter, what is the possibility of a Two which counts neither as one, nor as the sum of one plus one? A Two counted as two in an immanent way? Such is the problem of a scenario in which the Two is neither fusion nor summation. In which, consequently, the Two is in excess of that which composes it, without, for all that, annexing the Three. A real Two, since what composes it is only, by itself or in its being, a non-rapport which agitates the lure of the object.