What is "Beis ha'Yayin"?
Rashi: The Ohel Mo'ed. There, the details and explanations of Torah were given.
Seforno: It is Eretz Yisrael, the place of every pleasure and food without pain - "Zavas Chalav u'Devash" (Shemos 3:8).
Malbim (Melitzah): It is Ru'ach Hashem coming on Shlomo, and preparing him for Divine connection. In this entire Sefer, wine means that her Beloved gave to her to drink wine of Nevu'ah guarded in its grapes. It gladdens Nefashos when the Ru'ach comes on them.
What do we learn from "v'Diglo Alai Ahavah"?
Torah Temimah citing Maseches Soferim 16:5: Hashem gave Torah to Moshe with 49 reasons to be Metamei, and 49 to be Metaher 1 , like the Gemara of v'Diglo.
Torah Temimah citing Shabbos 63a: If two Chachamim are Madgilim 2 each other to learn Halachah, Hashem loves them.
Shir ha'Shirim Rabah 2:1(4): If an ignoramus mistakenly reads Ahavah as Eibah, e.g. he says v'Ayavta in place of v'Ahavta, Hashem says v'Dilugo (his skipping, i.e. mistake) Alai Ahavah.
Rashi: My gathering, that Daglani Elav (He drew me to Him) Alai Ahavah (I still remember His love).
Seforno: He made an encampment to fight [for me] when I was still beloved - "Lo v'Charbam Yarshu Aretz
Yerushalmi Sanhedrin 2:2 expounds this from "Mezukak Shiv'asayim" (Tehilim 12:7).
Rashi (63a): They gather each other to learn together. Tosfos ha'Rosh, Ritva - they contradict each other amidst debate, in order to delve into the Halachah.