>>149130448
I mean, it would certainly be a very different show and probably result in the show introducing a different male main character to end up as endgame for Star. Star and Marco are directly based on Nefcy and her husband, so if Marco was just her husband, a character who is her husband would have been introduced and ended up as Star's endgame.
Though we're taking it in a fetish sense, which your post clearly is, it depends on what you mean by "girl"... though not by much. Like, do you mean Marco got turned into a girl, or that he's a "girl" in quotes?
Either way, I feel like it depends on how you characterize Star. In this kind of scenario, Star needs to have as much or more energy than what she had in the early seasons. Later, "basically just an average teenage girl" Star would deflate the potential fun of this scenerio, and as a result a more "agent of chaos, my favorite hobby is finding wild warnicorns and riding them through walls" kinda Star is needed for that kind of Marco to work long term.
Basically only if Star is also made to be the the kind of girl who'd ask weather Marco wants to go clubbing to pick up some guys and making things real fun or stay home and try out all the new "toys" she just bought.