Persuasion is about choice and how the rigidity of class structure can hold people back from what will actually make them happy. It is specifically about the intersection of class structure and family pressures. Anne Elliot's arc is all about seeing past her family and friends' persuasions and incorrect judgements towards Wentworth, and learning to stand up for herself and her desires.
Wentworth is quite wealthy by the end, and therefore ultimately earns approval from Anne's family and friends, but Anne would've married him poor. Anne never stops loving him for a single moment of the eight years they spend apart. But she believes she has ruined everything by breaking off their engagement. She doesn't think he loves her anymore.
Aziraphale has been persuaded to leave Crowley, despite them clearly being in love with each other, because that's not suitable to Heaven. Heaven sees Crowley (and the other demons) as beneath them, just as Anne Elliot's circle believes Wentworth to be unworthy of her affections. Season 3 (if we get it) will be Aziraphale and Crowley's 7 years later. It will be Aziraphale seeing the error of his ways, and realizing he has been lead astray by Heaven. But it will also be Aziraphale being unsure if Crowley would take him back. In other words? The pining is going to be horrific.
And ultimately, it will be Wentworth's letter: "You pierce my soul. I am half agony, half hope. Tell me not that I am too late, that such precious feelings are gone forever."