Mr Light wrote:
Hey, I just realized something. Why did the series begin with Ted meeting Robin, if the story is him telling his kids how he met their Mother? Because he meets the Mother at Robin's wedding!
That's been the running theory. Robin must be instrumental to Ted meet the mother, because she makes a good starting point for his story to the kids. Otherwise, we would have started the show with Ted meeting Barney first (and by the time the series started, Ted had been friends with Barney for 4-5 years already).