You can't define what his dad's feelings are, and you shouldn't even try - that would be mind reading.
If your son wants to know why his dad is doing something or why he feels a certain way about something, you really can't answer that. The only reply to his questions would have to be that he needs to talk to his dad. I'm not saying you should tell your son to confront your H, just that it is not for you to tell him what his dad is doing or thinking.
My son was eternally asking me 'why dad this, why dad that..blah blah blah' and it had be turned back to him. Not my place to answer.
T19 M15 S19 XH47 M43 bomb12/4/07 PA5/07 S12/26/07 D final 11/17/08 Back together with no defined R 05/2010 confused....to say the least!!!