You can’t base your love of learning and even interest to learn on your chavrusa. Obviously a person can change chavrusas many, many times. It is not a shidduch situation and sometimes you just have to move on. What he did was not right, but there is nothing you can do about another person’s choices or actions. The question is what do you want to do? Do you want to learn geshmak or do you want to use this as an excuse to walk away?
Find someone you can appreciate and will appreciate you, that is the only way to grow in any situation, whether it is in a friendship, marriage or ben adom l’chaveiro. For whatever reason he turned his back on you he owes you an apology or at the least an explanation, yet it is not your job to get it out of him. That is his responsibility. What is your responsibility in all this? Is it possible that he wanted to learn with the other boy all along and didn’t just want to drop you and go with him? If so he went about it the wrong way. So he is wrong but that doesn’t mean that you have to do anything wrong in retaliation. If your goal is to learn then walk around this obstacle and find someone else to learn with and stop pining for this relationship.