That's too dramatic

Not really, he thinks the further away he is from this guy's pheromones the better the chance his life would return to 'normal'. This new omega life with its heat is too overwhelming

Actually, the problem is that his heat has begun newly and it's a confusing moment for him to accept it. Right that he thinks if he gets away he'll be normal and is embarrassed to accept this situation, but still that's wrong and there's no guarantee that there will be a stop to his heat once he moves away. His omega cycle has already woken so he needs to be marked by him (or any alpha he would prefer) at least to turn into normal now. (If that's the case in this work)