Joe Swanson, himself, admitted that Kevin had died in Iraq in a previous season, But he is alive and well now.
Bonnie: Jacques and I never had an affair!
Joe: Peter! You told me they had an affair!
Peter: That's what Lois told me.
Lois: No I didn't! I said she thought about having an affair!
Nora: Do you um... have protection?
Joe: Don't worry, nothing comes out of there anyway.