Here is an analogy. There is a co-student in your class who also happens to be rogue and your staunch enemy. He has been performing tasks to trouble you like talking behind your back, stealing from you and hitting you under false premises. You are a good student, hence the onus of ethics are a barrier for you. So you restrain yourself from hitting back your enemy.
This could be one way India and Pakistan are placed strategically. Socially speaking, you could complain to the teacher but she will ask for proof. Even if you collect some sort of proof, she would reprimand him or give him advice on not to continue on this path. Or she may ask you to solve your troubles with him on an individual level. Your enemy is smart too and he will come up with something that you have done to trouble him. The International community is like a teacher here for India and Pakistan.
Going to your parent is like the Indian Army going to the Indian government. The parent will advise you not get into conflict with somebody like him and get on with your work. On further prodding, you may convince your parents to talk to his. Like the Indian government talking to the Pakistani Government. Your enemy’s parents, on the other hand, don’t have much control over their child, the Pakistani army here. Hence your trouble does not stop.
Strategically speaking what should your response be? To neglect your enemy? This is really bad. His actions are taking away your peace; hence you cannot neglect but only pretend to do so. Once he knows that you are in trouble, he will continue with it. To try and be friends with him? If you can’t give him anything other than friendship, most probably he would reject it. You try it and fail. To strengthen your defence? This is important and the first step to be taken. Working hard to minimise your loss is a must. The lesser your loss, the lesser payoff your enemy gets and more frustrated he becomes.
You fear backlash from teachers and parents if you do something unethical to him. Why not teach him a lesson directly and do something that he hates, without leaving proofs. The knowledge that you have done it should be fine, proofs could be a problem. The general notion is that your troubles will increase once you do anything like this. But this is not true. Your troubles should decrease.
A good part of any conflict is psychological. For him, you are either a fool or a coward even though you can convince yourself of following ethics. Engaging with him by causing him trouble will hit on such psychological superlative and make him run for cover, which means divert his sole attention from troubling you to defending himself. An analogy here is that if you never attack in a football match, your opponent would automatically develop a habit of attacking you, however bad a team it may be. Only when you attack will they need to strengthen their defence.
This will not solve the problem. But in any case the trouble is going to stay so why not reduce yours and give some back to the enemy. Who knows his parents might come to yours to complain one day and be sent back disappointed. Or better, he will find another enemy along with you.
For those fearing a nuclear war, Pakistan is never going to use its nuclear weapons on India. Strategically it will be a blunder. Indian nukes can wipe out Pakistan or at least a good part of it. Hence nuclear war is not happening. Even the Mullahs should know it by now as well. So let us give the Pakistani army some trouble to reduce ours.
Note: I am not a defence analyst by any means. And have little information of India’s defence tactics. This is a spontaneous post.