The European Journey in American fiction

Ben Marcus's story in the current New Yorker, The Dark Arts, is in the genre (with which I'm familiar) of the young man's European journey of self-discovery - a genre that has evolved over a century or more from the Grand Tour education-of-a-gentleman, or woman, or of a naif, from Twain, James, et al. to the late-20th century version of a romantic/erotic journey from innocence to experience (this would also include mid-century versions of the Englishman's sojourn) - many of these made successfully into movies/plays (Cabaret, The Dreamers) and even some original movies e.g., Before Sunrise - but Marcus's is a 21st-century variant on this old theme - in which homoerotic elements play a bigger if not the major role. His story also has a unique twist - his hero is a 20ish man who goes to Europe not for self-discovery but for healing, from an undetermined autoimmune disease - he travels to E. with girlfriend and after some time in a few major cities they are to head to an experimental clinic in Dusseldorf where she is to stand by and help during his treatment. The catch is, they spat, for unclear reasons, he goes on ahead, she does not follow; he waits for days, weeks, starts his treatment, then she shows up and he disses, dismisses her - why is that? It would appear that the reason is: he has been staying in a men's hostel, has a homosexual encounter there (in a dreamlike state, he's not even sure it happened), and though he never explicitly says so we have to draw the conclusion that he has discovered his true sexuality, and perhaps? the cause of his "illness" and of their spat (he describes their sex as very mechanical and perfunctory. Two other works come to mind: the obvious comparison is with Magic Mountain, and main character is well aware of this, expecting spa-like treatment and not getting it; the second is Eugenides's The Marriage Plot: he and Marcus are fellow Brown alum (tho not contemporaries), and the overarching design of their works is similar: the European journey as homoerotic self-discovery.