what the eye doesn't see, the heart doesn't grieve over (idiom)
Definitions (粵典–words.hk)
語句
字面解睇唔到啲唔想見到嘅嘢，對眼都乾淨啲，冇咁閉翳、心煩，即係寧願唔睇或者直頭唔去睇啲覺得厭惡嘅嘢，同冇眼睇、冇眼屎乾淨盲差唔多，但係口頭少講 (to prefer) not to see something unpleasant; "what the eye doesn't see, the heart does not grieve over"; not as frequent as 冇眼睇mou5 ngaan5 tai2 or 冇眼屎乾淨盲mou5 ngaan5 si2 gon1 zeng6 maang4 in speech though; literally: what one cannot see, one can treat as clean
Definitions (Wiktionary)
phrase, idiomatic
to turn a blind eye to something