一转眼喜欢你这么久了
[yī zhuăn yăn xĭ huān nĭ zhè me jiŭ le]
This phrase roughly translates to 'In the blink of an eye, I've liked you for so long'. This indicates that the user has harbored feelings for another individual for what feels like an extended period but time passes quickly when being fond of someone or in love.