Koch's are men who all-too-easily find 'the one' and time after time, heavily pursue a particular girl (the Koch victim), usually until she becomes aware of the obsession.
In most cases, the girl/victim will dump the Koch when the obsession becomes too much to handle. Having said this, some girls enjoy being obsessed over and will happily marry a Koch.
Koch's will usually spend most of their time with the victim, ignoring friends until the likely breakup, at which point the Koch will come crawling back to previous friend circles in search of a new victim.
Kochs will often stop at nothing, stereotypically travelling long distances or even moving countries, in attempts to pursue victims. Needless to say, usually a Koch will quickly return to his home country after the Koch romance comes to an end.
Bill- "the British consulate are taking ages to grant me a visa so I can follow Bethany back to her home in London"
Bob- "tell them to hurry up and stop being such 'Kochblockers'... Wait dude is that the girl you met at the coffee bar yest?"
Bill- "yeah man, we're in love"
Bob (under his breath)- "what a Koch"