So, shallow describes something that is close to the surface — like the shallow roots

forlorn: When someone is forlorn it means that they not only feel miserable but simultaneously desolate because they also believe they are alone. 
shallow : Shallow likely comes from the Old English word sceald, which means "shoal," the water near a shoreline. So, shallow describes something that is close to the surface — like the shallow roots of a newly-planted tree or a person whose interest in someone or something isn't very deep.