"God bears long with the perversity of men, giving them ample opportunity for repentance; but He marks all their devices to resist the authority of His just and holy law. 8T 214.2"
"Or despisest thou the riches of his goodness and forbearance and longsuffering; not knowing that the goodness of God leadeth thee to repentance?"
Both passages discuss God's patience and the opportunity for repentance. The EGW passage expands on the idea of God marking resistance to His law, which is a logical extension of despising His goodness and longsuffering as mentioned in Romans.
"The Lord is merciful and gracious, slow to anger, and plenteous in mercy."
Both passages describe God's patience and long-suffering with humanity. The EGW passage speaks of God bearing long with perversity, while Psalm 103:8 describes God as slow to anger. This is a thematic parallel.