But this is not a recent phenomenon - it's a poorly-publicized fact of life that naive young men of each generation keep have been rediscovering for decades, perhaps centuries. Example: I read the autobiography of a certain chemical engineer (the name escapes me, will look it up later) who, while growing up in Southern US in the 1940s, described that he was shocked to discover that it was completely normal for a girl to date multiple boys at the same time.