A certain class of people will befriend you only so they can practice their “ignore you” games on you later. They will be effusive, friendly and kind at first, but as soon as they have achieved some familiarity with you, they will appear in your social sphere and then ignore you (but greet others) so that you guess what is wrong…These are sick individuals who get off on this because they feel serious insecurities deep inside especially in relation to you. The best defense against such people is not not making new friends, but not letting people get close to you fast, but if someone who became your friend but happened to turn into an “ignorer”, drop them immediately and do not talk to them anymore no matter what. A taste of their own medicine. If you don’t do this, their sick game will go on forever, and Sun Tzu (Sunzi) says nothing is a worse defeat than a protracted war with no outcomes.