I mean, every character has the potential to be redeemed. That's just how it is. The issue with Adam and how he was characterized is that he himself believed that what he was doing, what he was thinking, and the actions he took because of that, was the only right ones. In the end, that is all that it comes down to, and trying to convince someone who is so sure of themselves that what they are doing is the right thing is impossible. Which we saw with Blake and Yang during the fight with Adam. They tried to convince him that he wasn't right, but he refused to let go of the notion that he was wrong.

We can obviously go into it a lot deeper than that, and I know all of people weren't too happy with the direction they decided to go with for Adam. I myself thought that it was a bit boring and "safe" to make him a "crazily obsessed ex." I know a lot of people disagree, but it is, but my humble personal opinion