Group Scaling (Duo) Problems entering Act 3

Group scaling through the campaign needs to be looked at. I have been playing through the campaign with a friend as a duo and while the first two acts felt hard but fair we have hit a wall entering act 3. Monsters went from taking a few hits to die to being literal walls. I can understand a gradual difficulty increase towards the end but this was so egregious that my friend and I just quit as soon as we got to a safe space. From what I have read it seems that something is wrong with duo scaling in particular and this instance showed it.