It is a popular belief that when women live very close to each other or spend a lot of time together, the timing of their monthly periods will start to sync up and align.
The coincidences that revolve around this idea involve a kind of mysticism that helps us, as an analogy, to understand how this principle of symbiotic integration originates a synergy that contributes to the expansion and benefit of all the elements that compose it, either at the astral, ontological or physiological level.