It turns out that it’s a highly-adapted survival mechanism
Literally: heat – request – chill – truth / give up
Alternately: Wishing ardently for something, then rigorously investigating it or dispassionately facing its reality, especially the reality that what one wanted cannot actually be achieved. By extension, wishing ardently for something and then completely giving up on it.
Notes: In Buddhist texts, 諦 is used in contexts such as the Four Noble Truths (Japanese 四諦 = shitai). Despite the possible religious connotations of this phrase, though, its origins are unclear; the most I can find is that it seems to be a native Japanese construction.