没心没肺都怪以前掏心掏肺
[méi xīn méi fèi dōu guài yĭ qián tāo xīn tāo fèi]
'Heartless and careless is all because I once poured out my heart'. This indicates regret and reflection, implying previous deep love or sincere treatment leading to present emotional numbing, as if past kindnesses led to current indifference.