Kevin said that he loved her because she's wonderful.
Barney said that he loved her because she was broken.
Note the difference?
If Robin was a car, Kevin is looking to buy a Porsche meanwhile barney wants a v-dub from the 70s. OH! In every relationship, there's a Reacher and a Settler. Unless one or more parties are delusional about their role in the relationship....
With Barney and Robin they were both Settling, but with Robin and Kevin they were both reaching.