I read this book sometime in 80’s or early 90s. A young girl recently graduated from high school or boarding school is invited to spend the summer before college with a distant cousin who lives in an old house somewhere in the Midwest. I believe the girl is recently orphaned and has been left financially set. She starts to hear a piano playing at night and when she dons an Edwardian dress one night, She meets and falls in love with a young man from the 1910’s who loves ragtime music. I can’t remember if they meet through time slip or if he is a ghost. When she finds out he left for Europe on the eve of World War I, she decides to delay college and travel to Europe to find out what happened to him or perhaps find him. I remember her wearing bell bottoms. Been looking for this book for a long time and would appreciate any leads.