The person you sleep beside has an interior you will never enter. Not because they are hiding it, not because the relationship has failed, but because interiority is structurally private. They have thoughts they will never speak, feelings they cannot articulate even to themselves, a stream of inner experience that, by its nature, does not transfer. You can be told about it. You can infer it. You can love them across the gap. But you cannot occupy it. Long relationships either accept this honestly or pretend it away — and the pretending is one of the quieter sources of marital damage.
The pretending takes a particular form: the assumption that sufficient love, sufficient time, sufficient communication will eventually produce transparency. "We should be able to know each other completely." This belief, gentle as it sounds, is a violation of the partner. It pressures them to perform full disclosure they cannot honestly provide, and it sets up resentment when the performance fails. Real people are not transparent to themselves, let alone to anyone else. They carry interior weather they have not understood, motives they cannot name, contradictions that do not resolve. When you demand to know them completely, you demand they be less than human. The honest position is the opposite: I will know you as well as a person can be known by another, and that will be partial, and the partiality is not a problem to solve but a fact to honor.
Levinas frames the other as infinite — exceeding any totality you can construct of them. The face addresses you precisely because it cannot be contained in your concept of it. To love someone is, in part, to grant them this infinity, not to try to close it. The closing move — "I know you better than you know yourself" — is one of the most common forms of disrespect in long relationships. It feels like intimacy; it functions as colonization. You have replaced the actual partner with your theory of them and are now defending the theory against the inconvenient evidence of the actual partner.
There is a related, gentler error: thinking that because you cannot fully access their interior, you should stop trying to access it at all. The opposite is true. You cannot reach the bottom of them, but you can keep going deeper. The journey is the love, not the arrival. People who give up on inquiry because they cannot achieve completeness end up much further from their partners than people who continue inquiring while accepting the permanent gap. The gap is the condition of the inquiry, not its defeat.
The practical consequence of accepting interiority is humility — Law 0 — about your interpretations of your partner. When they behave in a way you don't understand, your first move should not be to explain them to themselves but to ask, with real openness, what was going on. They may not know. That answer should be acceptable. The mature partner can sit with "I don't know why I did that" or "I can't quite say what I'm feeling" without rushing to supply the analysis. The analytic rescue is usually about your own discomfort with their opacity, not about helping them. They can be opaque and loved at the same time. In fact, that is the only way they can be loved as a real person.
There is also a darker version of the inaccessibility: the parts of your partner that are genuinely unavailable to you not because of structural privacy but because of history. They have a relationship with their dead father you cannot enter. They have a grief about a child they lost before you met that you can only stand near. They have a religion or a politics or an aesthetic experience that lights them up in ways you do not feel. These are not problems. They are evidence the partner has a life that is not exhausted by yours. A partner whose interior was fully accessible to you would be a partner with very little interior — a being collapsed into the relationship, with nothing of their own. The richness you want in them requires the inaccessibility you sometimes resent.
Eros, again, depends on the gap. Perel's argument that desire needs distance is, at root, an argument that desire needs a partner with an inside you cannot occupy. When the inside seems fully transparent, the partner becomes a surface, and surfaces do not hold erotic charge for long. The partners who remain wanted across decades are usually those who retained a sense of themselves as more than the visible portion of the relationship — who kept a private life of mind, faith, work, or longing that the other did not fully share. This is not secrecy; it is selfhood. Without it, two people slowly merge into a single fuzzy organism that neither of them desires.
The mature position, then, is this: I will love a person whose interior I cannot enter. I will not try to enter it by force, by demand, or by the pretense of psychological mastery. I will keep asking, listening, updating my limited picture. I will accept that what they choose to share is real and what they choose to keep is theirs. I will not punish them for the having of an inside. And I will keep my own inside, too, so that when we meet, we meet as two worlds and not as one merged, transparent thing pretending to be intimacy. The gap is not the failure of love. The gap is what love crosses, again and again, without ever fully closing.