The seller decides when to stop viewings. If they believe they’re negotiating with a serious buyer, they may choose to pause or stop further appointments. However, a negotiation does not guarantee a sale—and many sellers want to gauge market interest before committing.
That’s why viewings often continue, even during ongoing negotiations. In such cases, the selling agent will indicate that the property is “under offer” (onder bod), but other interested parties are still allowed to submit a bid.
It’s ultimately up to the seller how to proceed. Importantly, the selling agent won’t disclose other offers—doing so could encourage overbidding, which is not considered fair practice.