DX had been working remotely ever since Kai Xin fell unconscious. After that second cardiac arrest where Kai Xin's heart stopped beating for 3 minutes, Kai Xin was placed in ICU for a few weeks to observe her conditions.
For some unknown reason, she continued to remain in a comatose state. However, there were no more attacks after that.
Once the doctor was absolutely sure that her body was completely fine, they transferred her to a normal ward.
DX was afraid that it might happen again and since then, he had never gone home. Even after Jack was discharged, DX still remained at the hospital with his wife. He was worried that Kai Xin would be scared if she did not see him when she finally woke up. She had always had an aversion to hospital, so he wanted to make her feel better by being there with her.
Even if she was asleep... Even if she did not know anything about it... He just wanted to be there for her.