电灯泡的感觉你不懂
[diàn dēng pào de găn jué nĭ bù dŏng]
Roughly meaning ‘you don't understand what it's like to be the odd man/woman out.’ Referring metaphorically to feeling awkwardly intrusive or third wheel-like in others' couples’ affairs; this term evokes a situation where the named feels superfluous or uncomfortable because they aren’t part of the couple dynamics. There is also an expression of frustration toward someone not understanding this specific feeling.