I've been looking up the trope and I've seen people tying it back to the 60s with shows like Bewitched and I Dream of Jeannie, but I don't know when the actual term "Magical Girlfriend" came into use. See, the concept is offhandedly mentioned by my heroine early in the story, and said story takes place in 1998. She's interrogating a 42-year-old "teenage" vampire she caught with a 17-year-old girl, and bemoaning that sometimes it seems like the seasons can't change until some creep rolls into town and tries to seduce a minor with the dreamboat vampire schtick or the plucky magical girlfriend routine. I'm trying to work out if that exact term existed back then, and if not, what she'd probably describe it as in that time period.
Both of those TV shows were orginally insipred by a movie called I Married a Witch, starring Veronica Lake, from 1942. As for "Magical girlfriend," I've never heard the term before. "Dreamboat vampire" is another new one on me.
Oh "dreamboat vampire" isn't a term as such, just how she's describing it. But Magical Girlfriend is the generally agreed-upon term for the trope/genre where an average guy winds up dating some manner of supernatural being. I just don't know how long it's been agreed upon.
If that comes from TV Tropes, then it isn't necessarily a saying, I think a lot of those are just named by whoever writes the articles for that site. In some cases they were already named, like I believe Manic Pixy Dream Girl was. But that isn't something normal people would call someone, it's more of an internet-era thing you see written online, not that people would say in conversation. But I wouldn't assume any of the TV Tropes names are going to be known to someone who hasn't read them on the website. There are some more well-known terms for the same idea (or simialr ones), like Twin Flame. Offhand I can't think of any more, but I'm sure there are some. Maybe like a Femme Fatale (beautiful seductive female who destroys men). What decade is the story set in? There may be some terms that would fit.
I mean, if you're talking about the real world, there is no agreed-upon term for that, because there are no magical beings in the real world. Unless you're talking specifically about things that happen in stories and movies. And even then I'm not aware of any well-known term for it.
If you want to use a term like that you could have someone use it and the other person look at them funny or ask "Say what?" and the first person explains what they mean. Otherwise I think you're going to have a hard tiem finding a well-known term for magical girlfriends. In reality when people want to get that idea across they'll say something like. "Dude, she's too good to be. true! My dream girl!" Or "She's an angel from above."
Well it has a wikipedia article, not a whole lot of tvtropes do. And yes I'm aware of the origins of manic pixie dream girl.
Here's the beginning of the wiki article: "a female stock character often associated with romantic comedy anime and manga series,[2] and is sometimes considered a genre of its own,[3] or as the leading lady of the "fantastic romance" genre, which combines the fantasy and romance genres." So, are these people talking about one of these genres? Or is that what your story is? If so, then your audience might be familair with it, but would it be a term used by characters in the stories? It would be an extreme breaking of the fourth wall to have the characters use these kinds of terms. I mean, that sounds like the Scream movies, where the characters are aware they're characters in a horror movie, and they talk about horror movie tropes. But then maybe you're writing postmodern comedy? That's what I'm trying to determine, if your story is supposed to be set in the real world, or in a postmodern setting where the fourth wall breaks down and people are semi-aware they're in a story. Because if that's the case, then they can talk about it all they want. But real people in the real world would only use those terms if they've read those wiki articles or TV Tropes, and generally only when talking about movies or stories. Unless they're noticing that real life is starting to feel a lot like one of those movies.