"Death by exposure to light" means: literally, death by exposure to light, and colloquial slang, which describes fragile vitality or strong dependence on specific growth environment. Often refers to the incompatibility between online dating and reality. The virtual network can't stand the impact of reality. But it doesn't just refer to online dating, it may also refer to some people who met online. They had a good impression, but after meeting, they felt that their impression dropped, which was not as real as expected, such as some dating networks, WeChat, Weibo and so on.