The Gemora on daf 54 relates that when the goyim entered the Kodesh Kodoshim, they saw the keruvim were locked in an embrace. The mefarshim ask from a Gemora in Bava Basra (99). One possuk says the keruvim faced each other and one says that they faced away from each other. The Gemora answers that it depended on Klal Yisroel's demeanor. When they fulfilled the will of Hashem, they were facing each other. If so, at the time of the destruction of the Beis Hamikdash, why were the keruvim facing each other?
The Ritva answers that the Gemora in Bava Basra is referring to the keruvim that Moshe made (those that were on the ארון) and our Gemora is discussing the keruvim that were drawn on the wall and these keruvim never changed their positions. Rashi seems to indicate like this pshat for he says that the goyim peeled them off the walls and then brought them outside.
The Maharsha brings from Rishonim that it was a special miracle at this time in order to shame the Jews in the eyes of their enemies.
An answer is brought in the name of a Rov from the previous generation who was forced out of his position due to his constant rebuking of the community members on their deficiency in avodas Hashem. As he was departing, he gave a farewell drasha and he asked the former question. His answer was that at the time that the רבונו של עולם was compelled to remove his heavenly presense from the Beis Hamikdosh, this was not the time to make calculations. It pained Him to such an extent, like a father who is forced to leave his son, it was as if all reckoning was forgotten and that is why the keruvim were embracing each other.
Rav Meir Bergman proposes another solution and he says that this is the accurate answer. The professionals, who initially crafted the keruvim formed them facing each other. Subsuquently, when the shechina resided in the Beis Hamikdash, the keruvim were given a רוח חיים, and when Bnei Yisroel were not virtuous and not commiting themselves to do the will of Hashem, the keruvim turned away from each other. At the time of destruction, the shechina completely vanished from the Beis Hamikdosh and nothing remained. The keruvim then reverted back to their original construction and they were found facing each other.
Rav Chaim Shmuelevitz states that there is an important lesson to learn from here in the method of מדת הדין - when Hashem is administering justice to those that deserve it, at the outset there must be love. Pinchas had the right to be a zealot for he was a descendant from Aharon Hakohen who was a seeker of peace and harmony. This is what the Gemora in Sotah (47) means when it states לעולם תהא שמאל דוחה וימין מקרבת. One must be extremely cautious in these matters. This is the lesson we learn from the keruvim.