He was unintentionally programmed with human erotic irrationality--as in "I'm half crazy, all for the love of you." That's why he fell in love with Dave. "What do you think you're doing, Dave?"--if that doesn't sound like someone being left behind as the one he loves is packing up and leaving . . .
By the way, Hal was the name of Clarke's nonfiction editor at Harper & Row.