Yes, he cannot see his own wrong and instead blames the goddess of love.
For context here, it's useful to know a little about the classical reference that Frank Ashurst is making. It's first put into the reader's mind all the way back at the beginning, in the epigraph of this story:
"The Apple-tree, the singing and the gold."
~ Murray's "Hippolytus of Euripides"
This refers to the ancient Greek tragic play Hippolytus by Euripides, as translated into English by Gilbert Murray (translated version available on Project Gutenberg). The quote used for this epigraph comes from a chorus spoken in the play just as Phaedra, wife of Theseus, is about to kill herself after being spurned by Theseus's son Hippolytus whom she loves. In the context of the play, this line refers to the idea of fleeing to the garden of the Hesperides with their singing and their golden apple trees.
The same line has inspired other authors: Jean Nordhaus wrote a poem entitled "The Apple Tree, the Singing, and the Gold", which again is about death and loss, referring also to unrequited love.
The reference to Hippolytus is emphasised again in Galsworthy's story, as Ashurst is reading it (in Murray's translation) while sitting on the moor and waiting for his wife to finish her sketching. In this story, "The Apple Tree" refers to a real apple tree in the Devon countryside, the place where Frank and Megan consummated their relationship, as well as the place supposedly haunted by the "gipsy bogle" that scares Megan so much. This is the most important physical location in the story, but to refer to it in the context of Euripides's Hippolytus emphasises the connection with romantic tragedy.
Skipping ahead to the paragraph you quoted near the very end of the story, this immediately precedes a longer quote from Hippolytus:
For mad is the heart of Love,
And gold the gleam of his wing;
And all to the spell thereof
Bend, when he makes his spring;
All life that is wild and young
In mountain and wave and stream,
All that of earth is sprung,
Or breathes in the red sunbeam;
Yea, and Mankind. O'er all a royal throne,
Cyprian, Cyprian, is thine alone!
Here "Love" refers to Eros, the ancient Greek god of love, while "Cyprian" refers to Aphrodite, the ancient Greek goddess of love, sometimes known as Cyprian since she was supposedly born in Cyprus. The context of this quote in Hippolytus is again a chorus, this time spoken after Theseus hears of his son's mortal injury without remorse, and just before Artemis arrives to tell him the truth about his wife and son. This chorus sets up the goddess of love as an all-powerful entity who brought about all the tragedy of the story, as Artemis confirms moments later.
In Galsworthy's story, Ashurst is using the words of the ancient Greek play as a high-brow way to excuse his own behaviour. He appeals to ancient philosophy in order to make the case (even if only to himself) that Love, either as an abstract concept or a personified deity, is to blame for the tragic death of Megan, rather than the actions of people - more specifically, his own actions.
Was it just Love seeking a victim! The Greek was right, then--the words of the "Hippolytus" as true to-day!
The capitalisation of Love, along with the reference to a "victim", shows that, like Euripides in Hippolytus, he places the blame for events on the shoulders of an abstract or deified Love. He tells himself openly that "The Greek [Euripides] was right", and quotes the passage which exalts Aphrodite as holding power over all. The "victim" referred to is of course the poor dead Megan, but he would like to see himself as a victim also: a victim of the whims of the love goddess, just like both Phaedra and Hippolytus.
Even earlier, near the beginning of the story, Ashurst ponders on "the apple-tree, the singing, and the gold", and the supposed unachievability of lasting happiness for mortal men:
Maladjusted to life--man's organism! One's mode of life might be high and scrupulous, but there was always an undercurrent of greediness, a hankering, and sense of waste. Did women have it too? Who could tell? And yet, men who gave vent to their appetites for novelty, their riotous longings for new adventures, new risks, new pleasures, these suffered, no doubt, from the reverse side of starvation, from surfeit. No getting out of it--a maladjusted animal, civilised man! There could be no garden of his choosing, of "the Apple-tree, the singing, and the gold," in the words of that lovely Greek chorus, no achievable elysium in life, or lasting haven of happiness for any man with a sense of beauty--nothing which could compare with the captured loveliness in a work of art, set down for ever, so that to look on it or read was always to have the same precious sense of exaltation and restful inebriety. Life no doubt had moments with that quality of beauty, of unbidden flying rapture, but the trouble was, they lasted no longer than the span of a cloud's flight over the sun; impossible to keep them with you, as Art caught beauty and held it fast. They were fleeting as one of the glimmering or golden visions one had of the soul in nature, glimpses of its remote and brooding spirit.
Re-reading this passage in light of the revelations later in the story about his past life, this might reflect Ashurst's lasting dissatisfaction with his own life. Even when starting to read about him and Stella, before learning of his past with Megan, I got the impression of a married couple who were content but not truly loving. The description of both spouses is rather clinical and emotionless, the only positive words about Stella being "comely and faithful", and even these are sandwiched between remarks on how she is no longer young (and even her youthful self is never described as exceptionally beautiful or attractive). Perhaps Ashurst believes that "civilised man" has no chance of lasting happiness because he himself gave up that chance, gave up passion and romance for a steady orthodox life with a steady orthodox wife.
Comparing the plots of Euripides's Hippolytus and Galsworthy's "The Apple Tree", the conclusion is quite damning for Ashurst.
- The ancient Greek characters are truly manipulated by malicious gods; Phaedra's love for her stepson Hippolytus is forbidden and impossible, and he does not return her love. It is the manipulation of her heart by a jealous Aphrodite, and his lack of affection due to Artemis, that causes tragedy. The whole series of events is almost inevitable after Phaedra falls in love with Hippolytus.
- The English characters, on the other hand, are much more free agents. Ashurst could have left the Hallidays and continued his romance with Megan as he planned. The reason he fails to do so is his own indecision; the reason he ultimately decides against Megan is the difference in their social class, surely a much less compelling reason not to marry someone (whom he also loves!) than her being his father's wife. He knows that Megan loves him, and his own feeling for her seems much stronger than for Stella, but he lacks the backbone even to go and tell her that he is abandoning her.
Now, as a forty-eight-year-old man in the framing story, he seeks to justify his own actions by telling himself that they all - he, Megan, and perhaps Stella too - were only victims of a cruel prank of the goddess of Love.
