It is very likely that the person you think slighted you was not thinking about you at all.
It is possible that the person you think is ignoring you might just be busy.
It is conceivable that the person you believe doesn’t like you might be distracted by other things.
It is difficult not to take things personally when you are dealing with other people. But the truth is most often that the person you think is plotting against you is not thinking about you at all. They are merely busy and distracted by the events of their own life.
Show grace to others the way you want to receive it.