Why does he lies at all?

I think the reason why he is lying is because one of two reasons: 1: The truth may hurt and hes trying to spare your feelings & 2:Just to get a reaction from you. I think that it would be a good idea to confront him. Because you know the truth, tell it to him indirectly. Question him with the things you know are true. Eventually, the truth will come out. You just have to wait patiently. On the other hand, some people just lie because its habitual. It can be a form of sarcasm because that person does not want to talk or trying to avoid the entire conversation. Just take it little by little. Lay down the trap, and he'll tangle himself in it. Good Luck!