Just like his wife when she was beautiful
When I read the lyrics to Merritt's track "Maria Maria Maria" on the Eban & Charley soundtrack, I realized that the story was a bit similar to the one told in "Babooshka," but with a gender switch. In "Maria Maria Maria," two lovers meet for an extra-marital affair, but in the final plot twist, after his lover departs, the protagonist removes his disguise and ponders, "I wonder if she ever knew her lover was her husband too." The wife in "Babooshka" decides to tempt her husband, as a test of their marriage, under the titular assumed name; first, she writes him letters, and then eventually she meets him incognito. Of course, he decides to be an unfaithful bastard. But, the situation isn't so simple: the husband is attracted to this mysterious siren because she was "just like his wife" before she became weepy, frigid, and dumpy.
The Magnetic Fields track "Wi' Nae Wee Bairn Ye'll Me Beget" has two main sources: the folk songs of Scotsman Robert Burns (David Jennings's page has links to MP3s of Burns songs) and the "shape-shifting couple" theme common to folk legends and songs, including "The Two Magicians." For example, this version by Steeleye Span is practically a (Wonder)twin to Merritt's ditty, lyrically - the chorus even ends with the line "A maiden I will die." As pointed out by Jennings regarding "Wi' Nae Wee Bairn...," "In live performance Stephin and Claudia...alternate in singing the lines in each verse, which brings out the dynamic of the song in sharper relief." Kate Bush's "Get Out of My House," a disorienting song about retreating and avoiding confrontation, also uses the "shape-shifting" theme. The woman turns into a bird to escape, but the man turns into the wind to hold her back and also to blow her a kiss. Then they both turn into mules, sterile and stubborn creatures, and bray until the song's conclusion.
Kate Bush - "Get Out of My House"