"It's Been a Long, Long Time" is a 1945 jazz standard by Jule Styne and Sammy Cahn that served as a popular homecoming anthem at the end of WWII. Famous versions by Harry James and Bing Crosby captured the emotion of romantic reunions, gaining modern recognition from the Marvel Cinematic Universe. It's Been a Long Long Time (Short 1945) - IMDb
This sentimental song became a hit at the end of the Second World War as wives and girlfriends welcomed returning veterans home.