[Freud] refuses to concede that the ego lacks definite boundaries, except in an inward direction. […] But there is an exception:

There is only one state, admittedly an unusual state, but not one that can be stigmatized as pathological—in which it does not do this. Against all the evidence of his senses, a man who is in love declares that ‘I’ and ‘you’ are one, and is prepared to behave as if it were a fact. [The emphasis is mine.]

There is something sad in this assertion. Freud has to stress that being in love should not be considered pathological. And, as if that weren’t enough, he then goes on to define the height of being in love as a state in which the greatest potential for the dissolution of boundaries between two people can be realized. He chooses this state rather than that of bodily union, in which it is surely in accordance with “all the evidence of the senses” that the border between “I” and “you” is blurred.

In adults, that is, the only infringements of boundaries recognized by Freud are in fantasy […].

Klaus Theweleit, Male Fantasies, Volume 1: Women, Floods, Bodies, History