SPANISH DUB.
Castiel: Te amo.
Dean: Y yo a ti, Cas. (aka I love you too/me too)
In spanish there are two ways of saying I love you. “Te quiero”, which is platonic, and “Te amo”, which is used in a romantic way, especially in TV and film, to make the intention of the characters extra clear.
Also. When Castiel pushes Dean, after saying goodbye, the “Cas, I-” was replaced by Dean saying “NO!”. Afterwards when he’s crying there is no weird ADR or birds singing in the background.