Was it proper for David to marry her so soon after Uriyah died?
Malbim (3, citing Mahari); No. He acted as if his lust was still pursuing him!
Malbim (26, 27): Yes - he needed to hide the fact that she became pregnant before Uriyah died. Now, people will think that she became pregnant amidst her marriage to David. It looked like David had grace on her, for her husband was a Gibor who died in war, and she found grace in his eyes.
Why does it say that it was bad in Hashem's eyes?
Malbim: Only Hashem knew what was wrong. Even though David did not sin with a married woman, and not through killing Uriyah, what he did was improper for Meshi'ach Hashem. He was not liable bi'Ydei Adam, but it was as if he stole her, like Perek 12 will explain.
