Yeah, ted whining about not being with Robin again was so tedious,
Well, she is the reason why he meets the mother.
In one of the episodes there was a flash forward where he is at the Farhampton station after the wedding. And the old lady asked him about it and he said something along the lines of "long story/it's complicated, don't want to talk about it". So he gets all Robinpressed and, I dunno, probably leaves early.
So expect more of that.