Like an Adulterer, but much worse. Someone who cheats on their spouse so much, they are akin to the Hitler of dating. It is rumoured that the original Adultler had as many as 6 million affairs in an event dubbed "The Hole-a-caust". Hole-a-Caust deniers say this is greatly exaggerated and that the actual number is likely much lower, perhaps 10 or 20.
"Well, duh... of course he cheated on you... he's a total Adultler"
"You sir, are worse than Hitler - you're an Adultler"
Source: adamfromtheblok, Canada, eh?