Adam is a prize idiot, and it's incredibly hard to swallow Karen putting up with that.
He left his teenage son in a boarding school so he could work in Singapore and didn't realise he was being bullied.
He married a woman half his age and quickly divorced her.
He got together with another woman soon after and was planning to have a baby with her, before cheating on her too.
He gets together with his friend's ex wife, and moves his son in - to his son's girlfriend's house! - without consulting him. Said girlfriend is pushed out of her own home and Adam doesn't realise that MAYBE they should leave.
Finds long lost daughter. Invites her to dinner, completely casually and with no regard for his son or her feelings if it goes badly.
I mean, what a dick!? Sure, parents shouldn't make every life decision based on their children, but they should make SOME.