Bella doesn't even know that Elspeth had plans to visit Downside until after she finds that Jane is offline, that wishing doesn't fix it. Elspeth is a grownup; Edward does not monitor her every minute of every day, does not report all her comings and goings to her mother.
It's Addy who tells her, uncharacteristically grave, after Bella makes the announcement that Aurum will be isolated until Elspeth finds a door. Elspeth rescheduled an appointment with Addy to go offworld.
And now Elspeth is not going to find them a door, because Elspeth is gone, might well stay gone till Jane is fixed, because time is only synced up due to Jane. And Bella cannot fix Jane. Elspeth might find a door after fifty years have gone by in Aurum.
Bella makes the revised announcement by brainphone to everyone except Jake.
Jake she tells in person. Jake she clutches by the shoulders while he sobs and shakes. Jake she offers to put to sleep so Elspeth will not come home to find him having done something regrettable. Because she will, eventually, come home. Jake she tucks into bed like she's his mother and sends into dreamless nothing so he doesn't have to suffer however long his imprint will be vanished where he cannot follow.
And then she goes to Edward and, because she is a vampire, she does not cry, but she does sob.