I can definitely relate. There's nights my wife and I get to bed and sorta just look at eachother and go "what the hell was that". Those days are hard.

I find the days that I forget myself and throw myself into trying to be a good dad are the days I find joy in fatherhood. Weekends especially I try to forget the stresses of work and productivity and everything else and try to spend as much time with them as possible. Playing, teaching, and learning with them.

Not saying it's universal. Just a datapoint from me.