Charlotte saves Wilbur at great cost to herself. She weaves her webs while she is already old and dying, asking nothing in return. White presents true friendship as an act of love that can be entirely selfless.
Charlotte's death is handled with great gentleness but genuine honesty. The book does not pretend she will come back or that death is not real. It is one of the most beautifully handled deaths in children's literature.
Wilbur never forgets Charlotte. Memory is presented as a form of love — to remember someone truly is to keep them alive in the most important sense.
Charlotte dies; her children are born. Three stay with Wilbur. Life continues in a new form. White presents this cycle with warmth rather than despair.