Why Maupassant's Alien Heart is a surprise among the many "salon" novels

In part Guy de Maupassant's last novel, circa 1890, Alien Hearts ("Our Heart," in the original, but at least Richard Howard explains his decision to translate the title thus), is about a failed love affair: the dilettante artist and flaneur Mariolle has fallen in love with Madame de Brune, a beautiful young widow who holds a week salon for artists and would-be artists, and she prides herself on being an a-list "coquette." Each of the men at the salon has fallen in love w/ her at at one time or another has thought he was the "favorite." W/ Mariolle it's different - he's the only one who she truly claims to love; he sets up a little "love nest" apartment where they meet every few days for sex, all the while keeping their relationship secret from others at the salon (including, presumably, her busy-body father). We expect, following the course of so many French novels, notably Flaubert's (he was close to Maupassant, we learn from Howard's intro) that one or both of them will tire of the relationship - but that's not exactly what happens. In fact, Mariolle continues to pursue her but is completely frustrated in that she never seems passionate toward him, only, we might say, tolerant and submissive. Maupassant can't say so directly, in his era, but it seems that Mme never experiences orgasm. She certainly is uninterested in Mariolle's affections and far less drawn to their rendez-vous than he is. He believes she is tired of him, but she swears that's not so - she loves him as much as she could ever love anyone - and that seems to be true. What's this about? It could be that she is afraid of and bitter toward all men because of the abuse she experienced, including sadism it seems, from her late husband. It could be that she is just non-passionate, more driven to the flirting and the controlling than to the sexual relationship itself. It could be that Mariolle isn't the great lover he thinks he is. Or, and Maupassant drops some hints on this score, it could be that she is drawn to women, perhaps even w/out being consciously aware of this. As with other French novels about salons, at times we want to throw up our hands and say can't you people get a life? Don't you have some kind of work to do? In this case - they do: there are real artists (including writers) who attend the salon, and the writer does so, he claims, to gather material. An important scene toward the end of part 2 of this novel involves a visit to the salon for a newly celebrated sculptor - we don't need Howard's intro to clarify that this character is a stand-in for Rodin - who delivers a long discourse about art and beauty and about his specific craft. The salon guests seem politely attentive and mostly bored - but it's a bright moment in the novel for us, as we get a glimpse of the mind of someone serious about his art, someone who's committed his life to creation and is a misfit in this society of "poseurs."