My former colleague told me his girlfriend is asking him for a diamond ring worth 100,000 yuan.

Even with a salary of several hundred thousand yuan a year, he's reluctant to spend that much money on it. He thinks the value depreciates by half the moment you buy it—a total loss.
But his girlfriend keeps pestering him every day, and he's still wavering about whether to buy it.
I told him: you haven't even bought a car or house yet. After marriage, she'll want those things too, plus bride price and other expenses. Without these, you can't get married anyway. So no matter how much you spend on her now, it's all wasted money. Even for items worth thousands or even hundreds of yuan, you need to think twice—let alone a 100,000 yuan diamond ring. It's pure IQ tax.
I really can't figure out what's going through the mind of a woman who demands a 100,000 yuan diamond ring from her boyfriend. Wouldn't she just ask an AI if diamond rings depreciate the moment you buy them? Gold or silver would be far better choices than this thing...