情不敢至深恐大梦一场
[qíng bù găn zhì shēn kŏng dà mèng yī chăng]
It means 'Afraid the love would turn out to be only a dream if being so deep'. It conveys people's caution and insecurity towards deeply fallen in love. People use it to express their fear that too intense of an emotion might just bring pain in the end and it is better to avoid getting overly immersed.