Why does it specify "ba'Leilos"?
Malbim (Melitzah): Shlomo prepared himself for Nevu'ah, night after night, until Hashem revealed Himself to him the second time. It says ba'Leilos (plural), for many nights she did not find Him (Nevu'ah), in spite of the many Tefilos are Korbanos during the 14 days of Chanukas ha'Bayis.
When did she not find her beloved?
Rashi: It is for the 38 years 1 that Yisrael were snubbed in the Midbar.
Seforno: During my darkness (night; Your anger) was for 40 days (after Chet ha'Egel 2 ).
Malbim (Melitzah): This begins the third Shir, until 5:2. Hashem did not speak to Shlomo from when he started to build the Beis ha'Mikdash in his fourth year, until he finished it seven years later. After being confined in the body for many days, she remembered her Beloved above and left her bed (body) to seek Him. She made many prayers and supplications and Korbanos (Melachim I, Perek 8), but did not find Him until she left the city.
Rashi (Devarim 2:17): From the Meraglim, until died all the men counted, Moshe did not receive Dibur (Hashem speaking to him face to face).
So says Rashi (Shemos 33:11, based on Yalkut Shimoni Ekev 855).
Why did she not find him?
Rashi: "Lo E'eleh b'Kirbecha" (Shemos 33:3).
Seforno: In the earlier days, I sinned, and You pardoned immediately after I repented. Now, in spite of confession, and Tefilah of Moshe and Tzadikim of the generation, I did not find Him, due to His anger.
Malbim (Melitzah): She did not find Him until she left the city, i.e. physicality, to connect with Kodesh. Then she had absolute Nevu'ah the second time, like she had in Giv'on, with love and dearness.
Malbim (Mashal): He was not in the city. Therefore, she did not find him until she went out to the Midbar.
