Proust's insight

In his famous article "Personal Identity", Derek Parfit quotes Proust:

We are incapable, while we are in love, of acting as fit predecessors of the next persons who, when we are in love no longer, we shall presently have become . . . . (Parfit's translation)

Parfit is interested in the notion of successive selves, which he thinks Proust employs, at least implicitly ("the next persons"), in this sentence. I am more interested in the insight about love that Proust expresses in it. In fact, Proust's insight does not have to be put in terms of the notion of a person or the self. What he seems to mean is that when we are in love, we are incapable of acting in such a way that we are prepared not to be in love any more. It is not just that we do not act that way; we are simply incapable of doing so, for the incapability is part of what it is to be in love.