To swear by him whom I protest to love,
That I will work against him."
Read—"when I protest to Love."
It is evident that Diana refers to Bertram's double vows, his marriage vow, and the subsequent vow or protest he had made not to keep it. "If I should swear by Jove I loved you dearly, would you believe my oath when I loved you ill? This has no consistency, to swear by Jove, when secretly I protest to Love that I will work against him (i.e. against the oath I have taken to Jove)."
Bertram had sworn by the Highest to love his wife; in his letter to his mother he says:
"I have wedded her, not bedded her, and sworn to make the not eternal:"
he secretly protests to Love to work against his sacred oath; and in his following speech he says:
"Be not so cruel-holy, Love is holy."
He had before said:
"——do not strive against my vows: