His Dark Materials by Philip Pullman - too many loose ends?

[Helene]

His Dark Materials Trilogy

The His Dark Materials Trilogy by Philip Pullman is absolutely fantastic but there seems to be a lot of loose ends at the end. For example, when Lyra and Will have to leave each other at the end in the Botanical Garden, what happens next? Do they ever see each other again? Is this really the end?

What about all of the children who are left alone in Cittàgazze because their parents have been killed? What happens to Dr Mary Malone after her experiences? Does she ever return? Why did Mrs Coulter and Lord Asriel have to die?

And the most pressing question of all, what happens to the alethiometer?