The line you have as "there is a reason strong, move slow" should be "there is a reason strong moves slow". He's saying that strong relationships are built up over time; you can't just blitz through all of the necessary stages in a new relationship by copying past relationships.
The line you have as "there is a reason strong, move slow" should be "there is a reason strong moves slow". He's saying that strong relationships are built up over time; you can't just blitz through all of the necessary stages in a new relationship by copying past relationships.