The two have been close friends for many years and tell each other everything.
Tips
grammar
Often used in the negative — 没有深交 (méiyǒu shēnjiāo, 'no deep friendship') — as a polite way to distance yourself from someone in trouble: 'I'm not really close to him'. Can also function as a verb: 与他深交 (yǔ tā shēnjiāo, to become close with him).
