Outlander question

I am obsessed with locating a book I read years ago. Of course, I don't remember the title or author and it's driving me crazy. Fellow readers, please help!!

I read it in the mid to late 90s I believe and think it was a fairly recent publication at that time. The novel started off in a sort of medeival setting/ era. The two main characters are living at an abbey. The girl is possible preparing to take vows and the young man is a preparing to be a monk, from what I recall.

The story follows these two throughout multiple lifetimes, as their souls are continually drawn together but unable to realize their love for one reason or another. It's been so long since I read it that I'm fuzzy on all the details.

I've combed through lists and other book sites. If it weren't for an old friend remembering the book as well, I would think I dreamed the whole thing.

So-- love story involving reincarnation. Not time travel. Literary fiction, not romance genre. Not part of a series. Originally pub'd 1995 or earlier. Any help or suggestion is much appreciated!