As I was carrying DF earlier today:
Me: I love you, buddy. Do you know that?
DF: (matter of factly) No, I don't know that, daddy.
When putting him to bed we go through a little thing right at the end. We say 'good-night' and 'I love you' and 'sleep tight'. Then I close the door and wait for a minute. He repeats one of the, usually 'good-night' and cries for a second. Then I open the door and 'good-night' him back. Then, and only then, he settles in.