Final answer:
The 'something not so important' likely refers to trivial issues which led to a breakup, contrasted with the unchanging and deeper significance of love and relationships throughout time.
Step-by-step explanation:
The passage seems to reflect on the idea that what's truly important in life, such as love and relationships, often remains unchanged despite the passage of time. The characters contemplate the significance of these elements, contemplating that while humanity may have advanced intellectually, the elemental human experiences such as love, friendship, and the ability to feel and connect emotionally are timeless.
The "something not so important" mentioned in the question is not explicitly defined in the provided text, but it could refer to the minor inconveniences or problems (like sour notes, broken bottles, or ripped cloths) that, in comparison with life's larger themes—like love—seem insignificant. Therefore, we interpret that the breakup mentioned may have been due to a trivial misunderstanding or a small issue that paled in importance when compared to the deeper connection of love that ultimately endures.