He gazed up and looked into the oval mirror above the sink and he could only see a ghostly reflection of himself . That was the moment when he knew he simply had to get away . He quickly grabbed a few change of clothes and packed them all into an overnight bag while the rest of the household were still fast asleep . He grabbed his phone and car keys , scribbled a quick note , pasted it onto the refrigerator , and went out the door soundlessly , as if he was a sip of ghostly smoke escaping into the early morning air .
According to the above context, answer the following question.
What may be the reason he left ?


He was having an affair .