Ryan "drove Kyon" away in order, in his eyes to protect Lucaon. This also had the support from Cecilia. This was at that time, and with the information they had the right thing to do, as at the end of the day Kyon was planted in their household by Edwin/Intron. They both accepted when Lucaon objected to this, and have moved on from their previous objections. In regards to Christoph, no Cecilia and Lucaon have not forgiven him. I think Ryan does feel affection for Christoph, and knowing what happened to Kyon, is now more aware of how Intron manipulates their servants. Knowing how close he is to Intron (being the brother of Edwin), Christoph is better to have on their side, and use, as he has information and power in relation and could be used as a bargaining chip.
Reading/following the story for Lucaon x Kyon, they both already suffered enough and deserve a happy ending. In my opinion, I cannot forgive Ryan and Christoph. Both essentially tried to keep Lucaon from being with Kyon. It was immensely unfair and hypocritical that Ryan easily forgave Christoph and dismiss his actions which by the way, harmed the Selvior family and Lucaon. On the other hand, he was an a** to Kyon and drove him to attempt suicide. I do not feel sorry for Ryan nor Christoph at all. Although, we can definitely blame Edwin for all of this. Why is Ryan x Christoph supported yet no one gets upset that those two tried to come between Lucaon and Kyon? If people are going for that pairing, then Lucaon and Kyon deserve happiness too.