I have absolutely no idea, all I know is that in the 15ish years since I last payed attention to Barbie and now (my daughter is a Barbie addict!) alot has changed, and those are some of the changes.
Midge and Ken are an item with offspring, Cricket and What-his-name have vanished and Barbie herself is single and now has more careers than most people knew existed. Not just the "cool" careers like she used to.. everything from Dr. Barbie (delivering Midge's latest bundle of joy), Film producer Barbie, Wedding planner Barbie, to grocery store cashier (I kid you not!) meanwhile Midge heads off to work and Ken takes the rugrats (In a minivan with working CD/MP3 player) to visit their grandparents (Complete with talking house).
Barbie is not completely without a social life though, In recent years she has met "Prince Charming" in her staring roles (yes, real movies, they were in theatres and sill still cost you $25 to buy) in Cinderella and Swan Lake.
I am sure if I actually felt like taking the time I could find out what actually happened... there is a website that escapes me atm (probably linked somewhere off the main barbie website) that has various stories and comic strips as well as mini movies and details about the entire history of Barbie and friends includig family histories and anecdotes from highschool/college/work/dating experiences... In a few of them Ken and barbie are still an item.. the mainstream toys (those for actual children) have Ken and Midge though (you're right.. this is a soap opera! ugh!)
It's frightening what a simple plastic doll created.. what's more frightening is that it's not children who are the main consumers of either the products or the stories. It's adults.. apparantly adults that are willing to shell out sometimes several thousand dollars a year on the latest collectors additions. One holiday edition (not the one availble in stores, the one from the "Exclusive Collector's Catalouge" that my mother-in-law had delivered 4 times a year) was selling for $1700. Average prices were between $150-400... scary!