Well, as has been written

...Buber posits an ontology based solely on
relation: "All actual life is encounter". In this way, he too
dismisses subjectivity by favoring neither a subjective I nor a
subjective Thou. Instead he privileges the mutuality of the relation
between the two subjects, all the while aware that this ideal
mutualism can degenerate into the monologic objectification and
instrumentalization of an I-It. I expands because Thou is boundless
and wholly other (as opposed to being merely the other of the I). The
I does not exist except insofar as it is in relation to either a Thou or an It.
               --Frank Garrett, Extreme Humanism: Heidegger, Buber and the Threshold of Language (2010)