So many manhwas with the trope of the saintess having black hair; Also, yes, this is the most GENERIC of GENERIC plots. There are hundreds of stories that go just like this.
Do you remember the hair colour of the villainess/MC at least?
THe more I think about it, the more I think it might be "Abandoned Empress"
- Korean Saintess transported to fantasy world, destined to be with blue-haired emperor (not a priest), MC still marries emperor (takes Saintess as empress, but MC as Queen). MC tries to stab Emperor after miscarriage, gets executed for treason. Regresses to past.
MC has white hair and often wears blue.
There are some jarring differences to what you described, but it's the closest I could think off.
I THINK SHE HAS PINK HAIR ಥ╭╮ಥ
OMG! MY DAMN SHORT TERM MEMORY ಥ‿ಥ
OOH! OOOH!! I REMEMBER SOME SCENE DAT DA SAINTESS SAYING SOME PROPHECY BUT DAT ALL SHE GOT IT FROM DA NOVEL SHE READ
SOOO.. I'M LOOKING FOR A MANHWA, ITS DA CLICHE TRANSMIGRATE MANHWAS, I WANNA RE-READ IT BUT I FORGOT DA TITLE ಠ‿ಠ
I REMEMBER SOME SCENES, BUT THEY'RE VIVID AS I READ DIS MANHWA AROUND 2YRS AGO?
HERE WE GO ಠ﹏ಠ
FL IS LIKE VILLAIN? AND THEN SHE WAS TRANSMIGRATE IN A NOVEL WHERE HER HUSBAND WAS DESTINED FOR THE SO-CALLED-SAINTESS, I REMEMBER THERE IS DIS SCENE WHERE WAS SUPPOSED TO MEET HER HUSBAND AND THEN SHE HID IN A GARDEN WHEN SHE SAW HER HUSBAND TALKING TO SOMEONE WHICH IS DA SAINTESS, THE SAINTESS I THINK WAS REINCARNATED TOO? DA SAINTESS HAS BLACK HAIRED AND BLACK EYES WHICH ONLY MARK OF BEING A SAINTESS. THERE IS ALSO A SCENE WHERE THEY SAID THEY FOUND DA SAINTESS SLEEPING UNDER DA TREE? (Not sure bout dis one) AND THERE IS DIS LIKE BLIE HAIRED PRIEST DAT ALWAYS ON DA TAIL OF DIS SO-CALLED-SAINTESS, AND THEN I THINK DA FL 'RUN AWAY' WHEN SHE SAW DAT SCENE.
HUEHUE! SORRY. DATS ALL I REMEMBER, BUT HOPE YOU STILL CAN HELP ME ಥ_ಥ