是我在一厢情愿凭什么怪你
[shì wŏ zài yī xiāng qíng yuàn píng shén me guài nĭ]
'It's my one-sided affection, how can I blame you' refers to someone feeling disappointed and frustrated because of unreturned love. They recognize it was their mistake to believe the love could be mutual and feel they have no right to complain or hold anyone else responsible.