The Dobler-Dahmer Theory is devised by Ted Mosby. In P.S. I Love You, Ted explains to his gang, that "If both people are into each other, then a big romantic gesture works: Dobler, but if one person isn't into the other, the same gesture comes off serial-killer crazy: Dahmer." This is further explained applying this theory on how Marshall asked Lily out by singing her a song he wrote at Wesleyan University.being was charmed by Jeanette finding him, that she is a Dobler, but she turns out to be a Dahmer.