Grope, reach for with one's hands, as in It was pitch dark, and I felt for the doorknob. [Early 1700s]
feel for someone. Sympathize with or feel sorry for someone, as in Tom was so upset that I felt for him. This usage was put as feel with by Shakespeare: "It resounds as if it felt with Scotland" (Macbeth, 4:3). Both senses of feel for are present in the somewhat sarcastic I feel for you but I can't quite reach you, meaning "Too bad, but I don't really feel sorry for you."