I follow Birch's transliteration of names.
Of the mysteries interrogated by literature, surely the greatest are love, death, and the divine.  The modern reader in particular is likely to understand the first of these as referring primarily to romantic and sexual love. In antiquity, however, and through the Middle Ages, friendship had a position nearly as prominent in constituting significant affective attachment. In Stories from a Ming Collection  friendship appears a primary measure of virtue while romantic love plays a far more dubious role.  The neo-Confucian model of friendship is not without Western analogues.
The book, a selection from the stories published by Feng Meng-lung  in 1620 as Stories Old and New, was written in vernacular language at a time when most literary works used Classical Chinese. During the Sung Dynasty (and even in the Yuan) prompt-books of professional oral story-tellers were collected and appreciated by the educated. By the early Ming scholars such as Feng were composing stories in the vernacular that imitated the traditional style, including addresses to the audience.
Most of the stories’ lovers are married couples, but the husbands’ and wives’ relationships strike the Western reader as singularly dispassionate. For instance, in “Wine and Dumplings” Ma Chou, when he moved in with Madame Wang is said to have “no hesitation in accepting her services, and seemed to regard it all as a matter of course.” (109-110) After declaring positively that he is “merely” her lodger, he is rapidly persuaded that marrying her is a prudent decision. (112) The same lack of passion is evident in the first story of “The Lady Who Was a Beggar” in which Chu Mai-chen’s wife leaves him solely because of his low social status. In the companion piece Mo Chi is approached by others who suggest he be married, and he considers the possibility in the most calculating terms: “I am not very well off . . .” (25) Not long after his marriage he attempts to kill his wife whom he has come to consider an embarrassment. In spite of his murderous attempt against her, when they are rejoined they live together “twice as amicably as before.” (35) Whatever level of affection that would come to, the reader hopes it will be sufficient, at least, to prevent assaults.
“The Pearl-Sewn Shirt” does portray sexual passion, but in a cautionary exemplum. Opening with verses recommending stoic acceptance and opposing sensuality, and a quatrain specifically counseling against adultery, the storyteller points a moral: retribution will come to those who give way to their desires. Chiang Hsing-ko is described as a young man of singular good looks and intelligence. When his father dies, the neighbors suggest his immediate marriage to Fortune to whom he had been betrothed as a child. They suggest quite sensibly that as a couple they could “help each other” (47), and he submits. When they are married, however, they are captured by passion. “From dawn to dusk they devoted themselves to pleasure.” At first this seems wholly positive. They are described as “a happy husband and a devoted wife” who “excelled other married couples ten times over.” (49) When he finally departs on a commercial trip, she behaves with scrupulous modesty for a time. An inadvertent exchange of glances with Ch’en Ta-lang, however, leads, through his bizarre and drawn-out stratagem,  to their love-making, followed instantly by their mutual infatuation.
In their first sexual encounter, when she believes him to be her older lady friend with a dildo, her pleasure is described in the most lyrical and extravagant terms. Their meeting is called the coming of rain to parched earth; the are the equal of legendary lovers of the past; Ta-lang “sent the girl’s soul winging from her body.” They are said to feel “a greater joy than the meeting of old friends far from home.” (74) This sentiment echoes the extravagant delight she had felt in the company of her husband. Even though they might have seemed a model of connubial bliss, it is now clear that the couple had taken too much pleasure in each other. Her very physical longing for her mate, the enjoyment they had found in sex, makes her vulnerable to an adulterous dalliance.
Through extraordinary coincidences, Chiang Hsing-ko discovers her infidelity and divorces her, then marries the widow of his wife’s lover, a certain Madame P’ing. He later remarries his first wife and the two wives and he are said to live together “in the greatest happiness,” “all joined in mutual love.” (96) The narrative’s unashamedly sensational and unlikely turnings are to the characters evidence that their lives are governed by fate.
If marriage is for the most part a practical matter and eros to be viewed with suspicion, what then becomes of the tidal flow of human attachment? The sort of friendship in “The Journey of a Corpse,” while very idealistic and philosophical, is at the same time this-worldly. Though little appreciated today, similar ideas about friendship were once current in European culture as well.
The theme of friendship is announced at the outset with a poem contrasting the “contract between hearts” that was friendship in the old days with the selfish egoism of the present. Wu Pao-an is a paragon of this sort of ennobling friendship even with a man he has not met. Seeking advancement, he writes a convincing job application letter to Kuo Chung-hsiang. His prose makes a sufficiently good impression that he is offered a post, but his patron Kuo moves out with the army and is taken prisoner before Wu can arrive. Feeling linked in mutual obligation, Wu Pao-an undertakes to ransom the man to whom he had written, devoting ten years to the labor and neglecting his wife and child. He eventually achieves this goal, and Kuo Chung-hsiang prospers after being set free. When his own wife dies, he sets out to repay Wu and endures arduous ordeals but finds his benefactor is no longer alive. All he can do is provide a funeral and care for Wu’s son “like a brother.” Eventually he retires and passes his position on to Wu’s son, fulfilling his “friend’s” request in the next generation.
The emphasis on friendship is familiar to the reader of Chinese poetry. Countless lyrics lament the pains of parting from a friend or the joy of reunion. The relationships among learned men, even excluding any explicit homoerotic element, must still have had something in common with the passionate friendships of ancient Greece. Indeed, the circle of Socrates’ disciples, united in admiration of the master’s mind, has much in common with Confucius and his crew.
If the quality of an individual may be gauged by his friendships, the “friends” in “The Journey of a Corpse” are an extreme test case. Their loyalty to each other has nothing to do with pleasure or social recreation or mutual benefit. It is based on men of virtue recognizing in each other value that justifies devotion even without personal acquaintance. The friendship recounted in the story is said to have excited such general admiration that Wu and Kuo acquired saintly status. In time a temple was built in Lanchou dedicated to them. (149) The word li, which in more ancient times had signified the proper magic ritual to accomplish sacrifices and the like, the sort of concern one finds in the Vedas, came for the Confucians to mean a new sort of ritual propriety that could be expressed in the transactions of everyday life. A story like “The Journey of a Corpse” concerns sages who are not hermits or monks, but householders in ordinary life, ordinary men who by their behavior rise to nobility.
The Analects opens with an appreciation of friendship and later details how friendship can be advantageous.  The network of hierarchical social relations that stabilize society are based on respect and mutual gain, but in the case of Wu and Kuo, loyalty required a display of self-sacrifice and fortitude to maintain a most exalted sort of friendship. Their philosophic dedication to principle would, perhaps, have found a sympathetic observer in Aristotle for whom the highest friendship can only be based in goodness of character. 
An amateur in Greek philosophy, I am even more at sea in Chinese thought, so I will not seek to untangle the notions of Plato and Aristotle on the one hand and Confucius and Mencius on the other.  The reader of the stories published by Feng can hardly avoid noticing, however, the most unromantic approach to most relations between the sexes and, in one story at least, the heroic model of friendship between worthy men, a friendship so demanding that it constitutes, for both friends a sort of heroic moral athleticism.
1. By this last term I mean to entail no necessary faith. I readily include essentially non-theistic views. Perhaps the term Ultimate Reality is preferable.
2. For a survey finding celebration of romantic love in spite of its obstacles in the society of the time, see Katherine Carlitz' review of translations by Patrick Hanan "Falling in Love: Stories from Ming China," in Chinese Literature: Essays, Articles, Reviews, Vol. 29, (Dec., 2007), pp. 169-171.
3. Subtitled The Art of the Chinese Story-teller, translated by Cyril Birch. I use the Grove Press edition. The question of the relation between this text and traditional oral story-telling is disputed. To Birch it is close indeed in spite of the fact that one of his stories derives instead from a wholly literary Tang Dynasty tale. To Patrick Hanan, Feng’s narratives derive not from village performers but from casual social story-telling among the educated. See “The Making of the Pearl-Sewn Short and The Courtesan’s Jewel Box,” Harvard Journal of Asiatic Studies, vol. 33, 1973. 124-153.
4. Apart from Stories Old and New Feng is the several vernacular novels as well as a variety of other works. He acted sometimes as a compiler of anthologies such as a book of folk songs and as a reteller of earlier stories as well as writing musical dramas and jokes.
5. In the course of this unlikely plot, which takes months (and dozens of pages) Dame Hsüeh becomes Fortune’s intimate to such a degree that the virtuous housewife is willing to, in effect, have sex with the older woman. When she discovers her lover was in fact a man, she seems altogether undisturbed, merely wondering “What am I to do if my husband should find out.” (74)
6. Analects 16, 4.
7. Nicomachean Ethics VIII. This view was widespread. See for instance, Cicero On Friendship or Laelius, 21.
8. Feng, I understand from secondary sources, was identified with Li Zhi whose philosophy was based upon Neo-Confucianism, though a critic of the orthodox Cheng-Zhu School. He is said to have been influenced by Wang Yangming (1472–1529), as well as the Taizhou School. Among the places I might begin reading on this topic are Tim Connolly, “Friendship and Filial Piety: Relational Ethics in Aristotle Early Confucianism,” Journal of Chinese Philosophy, 39:1, 71-88 and Shi Chang-yu, “Wang Yangming’s neo-Confucian School of Mind and the Growth of the Ancient Chinese Popular Novel,” Frontiers of Literary Study in China, vol. 3, no. 2, (2009), 195-217.