What if I told you I knew my teacher was cheating and did nothing about it?
Why wouldn't you say anything about your teacher cheating?
I didn't want others to dislike him, I had more interest in him.
Cheating is something that can be emotionally devastating for the person being cheated on in the relationship and is very wrong. If you knew about your teacher cheating, you should have told that person being cheated on so he or she could make an informed decision on what to do. Trying to protect your teacher's reputation is a noble idea but there also should be consequences for your teacher's actions when he or she does something wrong.
What? I just didn't want other to blame him and because it didn't matter.
While cheating is wrong then it is ok that you stay out of other peoples relationships. You could end up causing drama and it might spiral out of control and you could be blamed for something when you have done nothing. Keep your head down and focus on your studies.