In a Nutshell: “Gānxīn” is about your heart's agreement with a situation. It’s not about simple happiness like
开心 (kāixīn), but about a deeper, often hard-won, acceptance. Think of it as the feeling of “making peace with” an outcome. Crucially, its negative form,
不甘心 (bù gānxīn), is one of the most common and emotionally charged phrases in Mandarin. It means “unresigned,” “unwilling to accept it,” or “not content to let it be,” capturing a mix of frustration, regret, and a fighting spirit.