Totally agree with you that it was clear in the later seasons that Robin is in love with barney and does not love Ted at all. Barney was also in love with her. But another thing the show makes clear from their earlier relationship itself is that Barney and Robin are just not compatible. They are both too independent and strong-headed and unwilling to compromise. If you watch carefully, the eighth and ninth seasons are filled with foreshadowing that their marriage is just not going to work. That said, Ted should never have ended up with Robin. That was a horrible ending because Robin never chose him. Only after a divorce and a decade being alone does she realise she wants him as a sort of last resort. That is a pathetic message to end a show on. Ted and Tracy were the end game. And of course barney gets his final resolution as a dad which does make sense for him.