The speaker admits love is his sin, but immediately turns the accusation: the beloved’s virtue is hate, born from the same sinful loving. He doesn’t deny his fault; he forces the beloved to recognize their own. Those scarlet lips have sealed false bonds and robbed others’ beds, so reproof cannot justly come from them.
He then bargains: let my love be as lawful as your own flirtations. Plant pity in your heart so that, when it grows, you may be pitied in return. The couplet snaps: if you seek what you hide (pity or perhaps sexual favor), your own example may lead to denial. The mood is tense and bitter, yet beneath the logic lies a wounded, desperate appeal for shared mercy — a lover who turns the mirror on his judge, hoping common guilt will earn him the tenderness he craves.