"Nein" dahter allez wider sich
"La stan, Tristan, versinne dich,
Niemer genim es keine war."
So wolte et ie daz herze dar;
Wider sinem willen crieget er,
Er gerte widerr,siner ger.

Translation

"No", thought he, all against himself,
"Leave [her] alone, Tristan, consider [this,] come to your senses,**
It was never easy for anyone."**
The heart would ever have it so; (approx.)
He gets the opposite of what he wills, (lit.: Contrary to his will he receives.).
He desired against his own desire. (Or even: He strove against his own l___)

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