Our Gemara on Amud Aleph describes the visions of Rabbah Bar Hanna. In one of them he sees Mount Sinai and scorpions were encircling it. He heard a Divine Voice saying: Woe is Me that I took an oath; and now that I took the oath, who will nullify it for me? When he reported this vision to the sages, they rebuked him:

You should have said to God: Your oath is nullified. The Gemara explains: Rabba bar bar Ḥana did not nullify the oath because he reasoned: Perhaps God is referring to the oath that He will not flood the earth again. But the Sages would argue that if that were so, why say: Woe is Me? Rather, this must be referring to God’s oath of exile upon the Jewish people.

Yismach Moshe (Noach 20) wonders why God needed a rainbow to “remember his oath”? God needs no reminders! However, there is a teaching that when someone who makes an oath in response to a favor, he cannot rescind that oath without the subject’s consent (see Shulchan Aruch YD 228:20.) God made the oath and rainbow in response to the fragrant offering of Noach’s sacrifice (Bereishis 8:21). Therefore, this extra rainbow represents God’s making the oath in response to Noach’s offering, it was now irreversible without the subject’s consent. (Even though Rabbah Bar Hanna thought the oath was reversible, Yismach Moshe (ibid) explains his position.)

There are some kinds of love that are unconditional. God, like a parent or a lover, and humans walking in the ways of God, when so moved, can offer unlimited and non-conditional love that will never be broken.