WEST LINN, Oregon — When John Dekalb was young, making friends was easy. He walked up to other kids on the playground or sat near them in class, and all of a sudden, with very little effort, he had real pals. Later, his wife introduced him to her friends’ husbands, and they hung out as couples. But now Dekalb was 58, divorced, and the father of a 16-year-old who’d just gotten her first car. He had entire weekends to spend however he liked, but like many American men, Dekalb had few friends to spend those hours with.