Suffice to say that under qualia formalism both the feelings of oneness and separateness come from the properties of the mathematical object isomorphic to the phenomenology of one’s experience. In particular, the topology of such an object (and its orientability) may determine the degree to which one feels a self-other barrier. This is highly speculative, of course.
Analogous to the planetary habitable zone (neither too close to a star and thus burning nor too far and thus freezing), there might be a psychologically tolerable range for how much you believe in universal oneness. That is, it’s best to feel neither completely merged nor completely separate. Close enough that one can relate to others and not feel separate, but not so close that one’s existence feels redundant and cosmic loneliness sets in. Incidentally, this seems to be roughly the place at which Burners see themselves relative to other humans.
This from Qualia Computing, a true powerhouse of Whitmanic dynamism.