DISCLAIMER: This answer is purely my own theory. There are no authoritative commentaries that I know of which say that this theory applies to these pasukim, not to mention that this theory is even correct.
Taking the pshat of the pasukim, it seems to be talking about our relationship with Hashem, as His people. What does it mean for a relationship to be meaningful, vs. a relationship be meaningless?
I would say one approach would be to say that if we look at the word קרי, which means "it doesn't matter" (see this answer for full discussion), one way of looking at it might be viewing the relationship as "happenstance". There is no higher truth to the relationship, it just happens to be, and didn't have to be for that matter, ch'v.
It seems that if we treat our relationship with Hashem like this, He will, midda kneged midda, give us a relationship like that. Did we treat our relationship with Hashem like this? I don't know, I am not an expert, but it seems we did. One possible example might be that when Hashem said "I am yours", we kept saying "but we don't deserve" (קָטֹנְתִּי), and this is the equivalent of saying "we don't think You have any True connection to us, because if we don't deserve, then You will abandon us". Perhaps that is too nuanced, maybe simply worshipping idols could be considered treating Hashem like "our relationship doesn't matter". I don't want to speculate further on this, as at the end of the day, I am presuming that indeed we did commit this sin at some point.
However, my main point is to speculate on how Hashem has treated us בקרי. It seems to me that over the last 1000+ years, the close, personal and intimate side of our relationship with Hashem has been "pushed back against" to say the least.
For example, Tanach is absolutely replete with intimate statements from Hashem about His relationship with us. We are the apple of His eye, we are His children who He adores, His desire is upon us, He cries for us, and so much more. The gemara and midrash are full of very romantic aggadata, all of which place a very strong focus on how much we mean to Hashem. The Zohar, which was ostensibly written at that time, is perhaps the most romantic of all, solidifying to the most absolute that our connection to Hashem is meaningingful to the infinite superlative.
Then what happens? Well, the Zohar goes "underground". Then we seem to recieve a message that "all of this is a mashal, that only ignoramuses believe, and the truth is Hashem is completely beyond such petty things as love and relationships, and the truth is He doesn't need us, or our mitzvot, and it's all really just a kindness on His part, for our benefit". I am paraphrasing the Rambam's Moreh Nevuchim (at least, as it is understood by many, as is witnessed by many hundreds of answers on this very site who quote it). This hashkafa; this way of thinking has come to dominate the way we view "the truth" of Torah and our relationship with Hashem, even to this very day. It is a "way of thinking" that is shared בארץ איביהם, by the Greeks, the Christians, Moslems and many more.
This accomplishes an inner conviction that Hashem doesn't actually care about us, in His Truth, ch'v. We are but the lucky beneficiaries of a chance to get some eternal reward from Him, if we choose to follow the good advice He gave us in the Torah. Effectively, our relationship with Him is objectively meaningless, ch'v, and we can choose to make it subjectively meaningful to us personally if we want. This indeed is a "love that won't endure", as it is based on a "thing" - reward.
There is a huge case to be made that this is grave mistake. We either misunderstood the Rambam et al. by mistake, or perhaps this was "meant to be" and Rambam's hands were tied in the way he had to write things, and what he was meant to teach to his and future generations, perhaps to fulfil the "decree" of the pasukim in question (there is evidence for both of these claims, perhaps out of scope for this answer but I might make some footnotes later). I don't know, this is pure speculation on my part, but it makes a lot of sense to me. Feel free to upvote or downvote to express whether it makes sense to you too.
There is overwhelming evidence that indeed this understanding is mistaken, and our relationship with Hashem is completely essential. He needs us, as I went to great length to elaborate in this answer, and indeed finding out this good news could be the reversal of the decree, and a hint that we are close to Moshiach.
Note: I would like to spend time adding citations and other bits of evidence to this question at some point. Feel free to ask about anything specifically.