Teaching at a Catholic school and appearing on a reality show about a sham marriage apparently don't mix.

Randi Coy, the female star of FOX's "My Big Fat Obnoxious Fiance," has resigned from her teaching position at Pope John XXIII Catholic School Community in Phoenix. The 23-year-old first-grade teacher had been on unpaid leave from the school since late November, when she left to tape the show.

"It's simply a contractual decision," Mary Jo West, a spokeswoman for the Diocese of Phoenix, tells the Arizona Republic. "You can't serve two masters, and as a first-grade teacher, she needs to be there every day. It was a hard decision to make. We certainly wish her well."

The school's primary concern was that Coy's obligations to the show kept her away from her class for too long. Principal Bill Langley has also expressed doubts that "Obnoxious Fiance" -- in which Coy tries to win a cash prize by convincing her family that she's marrying a lout (played, unknown to her, by an actor) she met on a dating show -- would live up to the school's religious mission.

Coy tells the paper that she'd "hopefully, yes, definitely" like to return to teaching someday. For now, though, she's riding out her obligation to the series, which premiered to an audience of more than 19 million people on Monday (Jan. 19).

"I'm young and I did this for the experience, and who knows what's going to happen?" she says. "But right now, I'm just taking it day by day. I'm just going to see what happens."