I know a lot of Stelena shippers had a big issue with this scene because they think it is undermining that whole relationship like it was nothing. But that's not true. I loved this scene because Stefan is saying that yes she was his soulmate and they did fall in love but he thinks she came into his life not to be together forever but to bring him back together with Damon. He's saying that in the end his relationship with Damon is more important than his relationship with her. And I agree.