The speaker looks back on a relationship that keeps breaking and being rebuilt. It begins with a tender moment: saying "I love you" (the "three words") and sealing it with a kiss. From there the poem moves through the hard work of repair, patching "broken walls" with passion and pushing past both small and large mistakes.
The turning point comes when the speaker admits to kissing their partner while hiding secrets. That deceit sends them "back to square one." The image of a book with many pages but the same story captures the sense of being stuck in a loop.
By the end, the speaker takes responsibility. The mistakes are "foolish" and driven by "naive wants," and the speaker sees that those desires are clouding their view of what they already have. The mood is regretful and weary, but there is also a flicker of self-awareness. The speaker seems to recognise the problem, even if the poem doesn't say whether they can change it.