The 7th day of the 7th lunar month is Chinese Valentine's day. That's today (July 31st) this year. There is a touching story behind it.
It started with a mortal (Muggle in Harry Potter speech) orphan boy who grew up with his brother and sister-in-law. She was mean and sent him to shepherd water buffalo everyday. He is then called 牛郎 (NiuLang: the Buffalo Boy ).One day, he encountered an old water buffalo with a broken leg. He cared for it for months and nurture it back to health.
Few months later, he went back home and found a wonderful meal prepared and the whole hut cleaned up completely. His curiosity overcame himself after few more days of the same. So instead of shepherding as usual, he hid away to spy on his own place.
Gosh, a beautiful girl came. Cleaned his house and cooked. NiuLang jumped out and inquired. The girl, calling herself 织女 (ZhiNv: Weaving Maid), said she liked him. They married, had two kids, and were happy.
One day, thunders and lightening, ZhiNv disappeared. It turned out she is a fairy weaving for the Heaven Empress who is not pleased that she missed years of work, and more furious on she marrying a mere mortal. ZhiNv was summoned back. Gone and devastated NiuLang.
Suddenly, the old buffalo spoke. He is enchanted afterall. When he made a minor mistake up in the Heaven. They punished him by sending him down to earth. He broke his leg on his way down and was gratituded to NiuLang for saving him. That's why he introduced ZhiNv to NiuLang, without his knowledge, obviously. “Kill me and made a pair of shoes with my hind,” he said. “With them, you can go up Heaven and find ZhiNv.”
NiuLang did and found ZhiNv. Alas, Empress refutably wouldn't let them unite and sent ZhiNv away with a wave of her wand. But NiuLang ran toward her with all his might (sweat, tears, reaching out, determined, Rocky's training, Chariott of Fire, My Way, etc. all 9 yards). He was gaining and about to catch up.
Empress couldn't allow that. With another wave of her wand, a milky river appeared and separated the couple. NiuLang and ZhiNv were so, so sad.
Their love moved a flock of sparrows who gathered all the sparrows in the world and made a bridge with themselves. NiuLang and ZhiNv walked over the bridge and were finally together. Empress softened and made a concession. They are allowed to see each other once a year on that day, 7th day of the 7th month, over that sparrow bridge.
That's how Milky Way came from. That's why there is no sparrow on this day. That why it usually rain tonight (they cry in happiness seeing each others).