Because they failed to keep the first covenant, he wants to establish a new covenant they can keep

The Jews claim that the promised Messiah’s advent is being delayed as a result of their sin. Quite to the contrary, God here declares that he will make a new covenant or law, unlike Moses’ covenant or law, and that he will not be prevented from doing this by the fact that they have sinned. Indeed, precisely because they failed to keep the first covenant, he wants to establish another, a new covenant, which they can keep. Their sin or their breaking of the previous covenant will not deter him. He will graciously forgive their sin and remember it no more. – Martin Luther 1538