..4 years??? and he's still stonewalling you??
..he knows why ..and I think you do also..it's not complicated..
..he thought he could get some on the side
..he thought you'd never find out
..he got his ego stroked
..he was selfish
..he enjoyed the excitement
..he got to have a secret life
..he got the validation
..he got to live out a fantasy
..one can't read on this site without learning about all the reasons that are posted for the 'whys' of the affairs
..the list is a mile long.
He just doesn't want to admit to you, the reasons why he stepped out of the marriage, because.then he'd have to admit them to himself!
..so sorry you're here.. so sorry any of us are here!!