If Selden had come at Mrs. Dorset's call, it was at her own that he would stay. (1.5.8)
Does Lily want Selden, or does she want power?
How dreary and trivial these people were! Lily reviewed them with a scornful impatience: Carry Fisher, with her shoulders, her eyes, her divorces, her general air of embodying a "spicy paragraph"; young Silverton, who had meant to live on proof-reading and write an epic, and who now lived on his friends and had become critical of truffles; Alice Wetherall, an animated visiting-list, whose most fervid convictions turned on the wording of invitations and the engraving of dinner-cards; Wetherall, with his perpetual nervous nod of acquiescence, his air of agreeing with people before he knew what they were saying; Jack Stepney, with his confident smile and anxious eyes, half way between the sheriff and an heiress; Gwen Van Osburgh, with all the guileless confidence of a young girl who has always been told that there is no one richer than her father. (1.5.11)
This seems to be Wharton's view of society peeking through a variety of her characters' perspectives. She assigns this tone to Selden, but allows Lily access to it in certain, key moments.
That walk she did not mean to miss; one glance at the bills on her writing-table was enough to recall its necessity. (1.5.23)
If Lily's desire to marry a rich man truly is out of necessity, can it be judged as immoral?
As she did so, it struck her with a flash of irony that she was indebted to Gus Trenor for the means of buying them. (1.9.69)
This is the second time Lily pauses to reflect that the money she's using came from Gus Trenor. The other instance? When she donates money to Gerty's charity fund. It's interesting that these two decisions constitute polar opposites as far as Lily's morality is concerned.
But it is one thing to live comfortably with the abstract conception of poverty, another to be brought in contact with its human embodiments. Lily had never conceived of these victims of fate otherwise than in the mass. That the mass was composed of individual lives, innumerable separate centres of sensation, with her own eager reachings for pleasure, her own fierce revulsions from pain – that some of these bundles of feeling were clothed in shapes not so unlike her own, with eyes meant to look on gladness, and young lips shaped for love – this discovery gave Lily one of those sudden shocks of pity that sometimes decentralize a life. (1.14.50)
The wealth of Lily and the other women in her social circle is an ignorant one. These women have no conception of the universe outside of their protected and opulent world. This is a dangerous way to live, and leaves Lily completely unprepared for the challenges she faces in Book II.
"But things are not going as well as I expected," Mrs. Fisher frankly admitted. "It's all very well to say that every body with money can get into society; but it would be truer to say that NEARLY everybody can. And the London market is so glutted with new Americans that, to succeed there now, they must be either very clever or awfully queer. (2.1.31)
Mrs. Fisher is the novel's authority on the relationship between social status and cash. It's essentially her job to turn one into the other.
But now, at the actual crisis, this difference seemed to throw the weight of destitution on Bertha's side, since at least he had her to suffer for, and she had only herself. […] it was to Bertha that Lily's sympathies now went out. She was not fond of Bertha Dorset, but neither was she without a sense of obligation […]. Bertha had been kind to her, they had lived together, during the last months, on terms of easy friendship, and the sense of friction of which Lily had recently become aware seemed to make it the more urgent that she should work undividedly in her friend's interest. (2.2.64)
It's clear that Lily genuinely does want to help Bertha – which makes it all the more frustrating that Bertha turns on her helping hand. This is not the first time Lily has felt intense personal obligation in return for financial help.
If Judy knew when Mrs. Fisher borrowed money of her husband, was she likely to ignore the same transaction on Lily's part? If she was careless of his affections she was plainly jealous of his pocket. (2.4.42)
This just drives home the point that a man's job in the world of House of Mirth is to make money, not to love his wife. That explains Judy Trenor's discriminatory jealousy.