It's great you can cut him that break. Quite often people get caught out in what appear to be "lies", but which actually reflect an inability to come forward about something that, at the same time, can't stay entirely covered up either. Inventing a scenario that works for your guy allows him to regain some sense of control over a situation that clearly bothers him a lot, even if that control is only an illusion.
If you give him space instead of confronting him, you are also giving him room to negotiate with himself and you over all this. I wouldn't be surprised if one day it all comes tumbling out, but that has to be at a time when he feels he can face whatever consequences or reaction he thinks he may get. So again, looks like there's something serious under this lid.
Nobody living can ever stop me
As I go walking my freedom highway.
Nobody living can make me turn back:
This land was made for you and me. (Woody Guthrie)