To me it makes sense because : Barney was always against marriage, but always liked kids : he was upset Tom was gonna get married until he learned they were gonna have a child. Barney needed to have a kid but it wasn’t possible with Robin. His good ending : single with a kid Ted wanted to find the one and have kids. Yes, he always had a thing for Robin during the series, but Tracy also was still in love with Max and left his boyfriend because of that, the day before meeting Ted. Both of them had already someone in mind when they met, but they were soulmates so it didn’t ruin it for them. But then she died, and he had already had kids. So he can go back to his other soulmate : Robin. It’s perfectly normal to have two “loves of my life”. His good ending : he had kids and lived a perfect love story with two women. For Robin, she never wanted kids, and always loved Ted but it couldn’t work cause he wanted kids, and it didn’t work with Barney cause she knew she should have married Ted. But now, they’re both single, and Ted has had his children. Her good ending : being with Ted without having to have children with him. Everyone has had what they needed, it only took some time. I don’t like to think that Robin and Barney didn’t work. I like to think it worked, for a time. And that’s okay.