I'm sure part of Ethan wants to forget about all of this and rekindle their friendship. The problem is Ian isn't trustworthy anymore. His actions have totally eroded any credibility he had. He's proven he's the kind of guy who will be your friend for eight years and then trying to publicly crucify you alongside your worst enemies. It's not just aggressive, it's also deceptive and vindictive. And he did it all with this thin, transparent veneer of being the nice, meek and well-intended beta who just wanted to help Ethan. This wasn't just a sudden crash out when emotions go high, this was a prolonged and crafted campaign.
Once you've proven you're capable of that kind of treachery, it takes a lot to come back from that. The kind of goodwill effort I don't think Ian is even slightly capable of, even if he wanted to. Forgiving is one thing, forgetting is another.