为她流泪不如为狗流血
[wéi tā liú lèi bù rú wéi gŏu liú xuè]
This implies a harsh realization or cynical attitude towards love where one feels sorrow from loving someone (usually romantically, specifically a 'her') brings more pain than caring for another creature (in this case, a dog). It suggests feeling unappreciated and expresses disillusionment about unrequited love.