Plot twist, Adrien is Felix all this time and vise versa since they used to dress alike as kids that gets to confuse both parents.
Amelie is more like Adrien like Gabriel is more like Felix.
Just a theory-
"Is father ever happy though? I still don't understand why he can't just let mother go. I don't want to sound heartless.....but as much as I miss her we can't undo what happened."