What are your thoughts ?

My friends and I were having a girl chat the other day and the topic of crushes and rejection came up. Some of us believe that if someone you had a crush on rejected you, there is no reason to be friends or be cordial with them. It doesn’t have to be drama but it’s perfectly fine to act as if the person doesn’t exist. However, some other people thought it’s rude to be that way and at least being cordial with the person is the best way to go. What are your thoughts ?