My partner goes completely silent during arguments and I cannot get anywhere. What is happening?

What you are describing is most likely a genuine shutdown rather than a tactic, and the distinction changes what to do about it.

Under enough conflict arousal, people vary a great deal in what happens next. Some get louder and pursue; some go into a state where heart rate climbs, working memory narrows, and the capacity to form a sentence about feelings drops away. From the inside it is closer to going blank than to refusing. From the outside it is indistinguishable from stonewalling, which is why the pursuing partner usually escalates — and escalation deepens the shutdown, so the pattern reliably gets worse rather than resolving.

The recognisable version of this is a pursue–withdraw cycle, and it is one of the most consistently documented patterns in conflict research. Both halves make sense on their own terms: you escalate because silence reads as not caring, they withdraw because intensity reads as danger. Neither of you is doing the thing the other one thinks you are doing.

What tends to help, and the order matters. Agree in advance — not mid-argument — that either of you can call a pause with a fixed return time, twenty or thirty minutes, and that the return actually happens. The fixed return is the part that does the work: an open-ended pause reads as abandonment to the pursuer, which is why "I need space" usually fails. Then re-enter with the smallest piece rather than the whole grievance.

The part you flagged yourself is worth taking seriously: escalating to get a reaction is the move that keeps this cycle running, and it is also the one you have direct control over. Whether they will do the pause reliably is the thing to find out — if the silence is consistently followed by a refusal to ever return to the subject, that is a different pattern and a harder one.

One thing worth checking on your side, because it changes the reading. Notice whether the intolerable part is the argument being unresolved, or the not knowing where you stand. If a pause is bearable when you are confident the relationship is fine, and unbearable when you are not, the escalation is being driven by uncertainty about the bond rather than by the topic. That is a well-mapped pattern and it responds to something specific: reassurance about the relationship before returning to the disagreement, which sounds like it should not work and reliably does.

Both of you being able to name your own half out loud tends to defuse it faster than either of you changing behaviour by willpower. "I go blank and cannot find words" and "silence makes me think we are in trouble" are both much easier to hear than the behaviours they produce.