As we all know, near the novel's end Tess kills Alec, reunites with Angel, the two live in a room at a vacant mansion (Bramshurst Court), and part at Stonehenge. In these few days Tess believes she's experienced the bliss for which she longs.
A new interpretation of Chapters 57-8 seems reasonable and is suggested. In this interpretation, after rejecting Angel and killing Alec, Tess remains in her lodging a relatively short time before being captured there by police. The intervening events Hardy described were all a dream state fantasy in which Tess only imagines her happiness.
Supporting this interpretation is that during this imagined episode, Tess seems to have no purpose other than to be with Angel in the moment, avoiding thoughts of the past, the future and exterior world. At Bramshurst she keeps to a darkened bedroom. Hardy is describing an essentially spiritual existence in which there's only she and Angel expressing their mutual love. What Hardy describes is perfect fulfillment without clutter, but as we know realistic fulfillment comes imperfectly and not entirely as we imagine.
Tess' happy moments, entirely imagined in my view, can't have a future because she's certain that when Angel objectively takes stock of her he'll despise and reject her again. She's now not only a woman with a blemished premarital past but an adulteress, a virtual prostitute and a murderer. Angel might be more enlightened than earlier, but Tess is justified in thinking Angel can't accept her now. In reality she can't chase after Angel because as much as she longs to be with him, his rejection of her would be unendurable.
By Tess relying on her fantasy of fulfillment rather than attempting the impossible real one, a reader's appreciation of her terrible misery is deepened and intensified. In believing her fantasy was real, Tess reveals to us how emotionally withered and damaged she's become. She reminds us of the fatally wounded pheasants whose agonies she mercifully ended by breaking their necks. Tess gladly anticipates the same from her hangman.