This sentence is from a husband on an English speaking forum for advice about her wife who has dementia.Dementia and wandering
My wife, 71 has lost all interest in anything other than walking up and down our street. She has wandered on 2 occasions when I had to call the police to find her.
So, if I understood correctly, first, she left the house and then he had to call the police.
But then, why does the husband use "when" instead of "and then"? The use of "when" gives the impression that 2 events were happening at the same time, whereas they weren't. First, she left the house. After that, he called the police.
Is it still ok to use "when" in such events that happened one after the other instead of using "and then"?