40's or 50's movie with a teacher whose student goes on to be the president?

My wife is losing her mind trying to remember the name of this movie. The teacher falls in love with someone else (another teacher?) at the school, marries them and when he goes to WWII, and never returns. One of the students tries to find her for years and she finally ends up finding him right before his inaugural speech. He says he has been looking for her and that she is the best teacher he ever had.