Mapping the sexual / romantic network of a high school

The diagram that illustrates research into the romantic entanglements of an entire high school look remarkably to my eyes like molecular chains. I realize that some of that is a matter of choices about how to visualize data, but comparing the smalelr groups to the giant daisy chain (the popular kids?) really gets across the idea that these smaller units link up to create the bigger ones.

I'd be interested in seeing a time factor introduced to these shapes. Also, shouldn't there be some free-floating single atoms as well? (It's been a while since I was in high school, but aren't there always some people in any given year without partners?).