Songs are as sad as the listener.
When you're sad and upset, it's really easy to see that sadness in everything. During that time minor chords in music and dark tones in drawings resonate better with us. It seems that the whole world grieves with you when in fact the only thing that changed is your perception.
That's why people love sad songs. When you are listening to them you are sure that every line is written about you and about your sorrow. For some reason increasing this sorrow feels good. But it's much better to realize that everything around you is so lovely, better to stop being sad and start seeing beauty and goodness. In that case the song you were listening to won't seem so sad any more and you will start to notice the positive in it.
Drew this piece on the page from 19th century music sheets.