I remember seeing a movie, an old period drama (colonial), about two sisters. One sister is engaged to be married while the other sister is desperately in love with her sister's fiancée. In the end, the first sister feels a strong calling to become a nun, leaving her fiancée available for her lovelorn sister.

I am revising a question I asked yesterday about an old period drama (possibly Civil or Revolutionary War era) about two sisters who share the same love interest. The eldest sister is pursued by a young military officer and they become engaged. The young officer goes off to war and there is some kind of letter (or letters) involved, I think, although my memory is sketchy, at best. Meanwhile, the younger sister realizes she is desperately in love with her sisters fiancée. In the end, the eldest sister feels a strong calling to become a nun. She goes off to a convent which ultimately brings the younger sister and the officer together. I remember one particularly poignant scene when the young officer searches for his beloved at the convent. When he finds her, she must try to make him understand her overwhelming need to give her life to God. Both women are beautiful in their long period gowns, and the young man is dashing. I am familiar with most famous stars from the 40's and 50's, but I can't, for the life of me, put a name, or even a detailed description to either of these women, or the man. I'm not sure if the movie was black and white, or color. I'm not even completely sure it was an old movie, but it certainly had the look and feel of an old movie. I hope someone can help?? This one has been haunting my for some time now.

"Devotion" 1946 (B&W) starring Ida Lupino, Olivia Dehavilland, Paul Henreid. This movie fits the bill, about the "Bronte" sisters, except there are no editorials or reviews that reveal the ending. One review eludes to a surprise ending, and several reviews comment on how the picture does not accurately represent the sisters, or their lives. The "letters", I believe, may actually be snippets from the famous sisters writings. I have purchased the movie and am very excited about possibly answering my own question by my recent research on Amazon. From my recollections, Olivia Dehavilland seems like the perfect actress to play the ending convent scene as I described!
(For some reason, my question was posted under someone else's name)

If not the movie tancindy suggested, maybe Green Dolphin Street? Definitely a convent and a letter, both much involved.
Movie Review - Green Dolphin Street - ' Green Dolphin Street,' Based on the Goudge Novel, Stars Lana Turner, Donna Reed and Van Heflin at the Criterion - NYTimes.com (http://www.nytimes.com/movie/review?res=9804E1D8123AE233A25755C1A9669D946693D6C F)

Thank you, smearcase! Having read the reviews for Green Dolphin Street on Amazon, I believe this is exactly the movie I am looking for. It's curious that I remember the convent scene over an earthquake and tidal wave, but aside from that, this movie seems to be a perfect match! I can picture Donna Reed as the quiet sister in the convent as easily as Olivia Dehavilland. The mix up with the two sisters names in the proposal letter is the clincher that has me totally convinced that this is, indeed, the picture I am looking for! Many, many thanks, again!
tancindy