I was reflecting recently on something I’ve felt myself and seen in many clients: that even when you know your relationship is over, your body might still ache with a different kind of grief — the loss of the other body. The loss of the nervous system pattern you've known.

You see when we end a long term relationship, whether it be an intimate or close platonic relationship, it is not only the financial and logistical separation and negotiation that happens. Our bodies keep the score and there is a physical separation of nervous systems that have entrained to each other.

Our nervous systems attune to the bodies we live with. Even if the relationship was painful or over long ago, your body might still long for their touch, their presence, even their smell.

This isn’t about wanting the person back — it’s about missing the co-regulation, the shared rhythm your nervous systems built together. It’s why sleeping alone can feel painful. Why your skin aches. Why you cry and you don’t know why.

Entrainment is when two nervous systems get in sync with each other, a bit like two clocks ticking together or two metronomes lining up. When you live with someone, your breath, heart rate, stress patterns, and even sleep rhythms start to line up with theirs. Your bodies learn each other. That’s why, when they’re gone, your body still remembers that pattern — and it can feel strange or even painful until you find a new rhythm.

The entrainment of nervous systems, especially in close relationships, is such a subtle and powerful force. It’s part of why even dysregulated relationships can be hard to leave — because the body gets patterned into that rhythm, even if it’s chaotic or unpredictable. I some times think of this phenomena as co-dysregulation.

In healthy relationships, this entrainment creates a deep sense of safety and grounding. But in any relationship with proximity over time, the nervous systems begin to sync — breath to breath, step to step, sleep cycles, even hormone levels. It's primal. It's ancient. And when it’s gone, the body doesn’t just let go because the mind says it should.

When this stops, the body reacts with disorientation, grief and longing.

This isn’t about missing the person romantically or doubting the decision. It’s about the withdrawal of co-regulation — a physical and energetic loss. Where there was once a warm body, there is now space. The nervous system goes through a recalibration, and sometimes, a kind of withdrawal.

We can experience shame and confusion around this.

Many people feel embarrassed or confused by their grief, especially if they initiated the separation or felt clear. They may wonder: “Why am I crying? Why does my chest ache? Why do I feel so alone? It is important to normalise that this is nervous system memory, not a sign that they’ve made the wrong choice.

What are some practices that can support you?

Orient to touch — a hand on the heart, a warm wrap, a pillow beside your body in bed.
Use scent, rhythm, and sound to create new patterns of regulation.
Let the body feel the grief — let the tears, the ache, the longing move. The body needs to move downward to express grief so sometimes, lying on a soft nest of pillows can be a really supportive way to do this.
Use nature, animals, breath, or trusted others to co-regulate in new ways.

Remember, relationships ending can be both a liberation and a loss. Our bodies are sometimes slower than our minds when it comes to moving on and they ask us to honour what was, whilst we are moving into what is next for us.

The invitation here is to trust the wisdom of your body and honour this unique grief without judgment.