Please feel free to agree/disagree and share your favorites in the comments.
(In no particular order:)
Anne Shirley and Gilbert Blythe from Anne of Green Gables by Lucy Maud Montgomery.
The Fault in Our Stars by John Green.
Despite the tumor-shrinking medical miracle that has bought her a few years, Hazel has never been anything but terminal, her final chapter inscribed upon diagnosis.
But when a gorgeous plot twist named Augustus Waters suddenly appears at Cancer Kid Support Group, Hazel’s story is about to be completely rewritten.
Tommy and Tuppence, two people flat broke and out of work, are restless for excitement. They embark on a daring business scheme—Young Adventurers Ltd.—"willing to do anything, go anywhere." But their first assignment, for the sinister Mr. Whittington, draws them into a diabolical, political conspiracy. Under the eye of the elusive, ruthless Mr. Brown, they find themselves plunged into more danger than they ever imagined.
Anne Elliott and Captain Wentworth from Persuasion by Jane Austen.
When later Wentworth returns from sea a rich and successful captain, he finds Anne's family on the brink of financial ruin and his own sister a tenant in Kellynch Hall, the Elliot estate. Al the tension of the novel revolves around one question: Will Anne and Wentworth be reunited in their love?