爱如鱼饮水冷暖自知
[ài rú yú yĭn shuĭ lĕng nuăn zì zhī]
This means 'Love, just like fish know if the water is warm or cold,' highlighting that love involves personal, intimate experiences that only the individual can truly feel and comprehend. It speaks to personal experience with emotions being something profoundly individual, where only they understand their own situation.