I'm assuming that this line means that Love can happen quickly and you never know how long it will last and if it ends, forgetting it takes time because you were just in love and now it's over so you have to take time to processs that it's over and forget what you've been through. Sorry if it doesn't help.
Answer:
American Flag : Freedom and Unity
White Flag: Surrender and Humility
White Dove: Peace and Love
Red Heart: Love and Compassion
