What does it mean when a friend in your friendlist in facebook deleted you as friend?

I uploaded pictures of my close relative in my facebook.I didn't know that all the pictures would be post to his friends.He is in the swimming pool swimming and.all them are nice.Just plain swimming in the pool and some close ups.When his friend commented "wow you are swimming",he didn't like it and he deleted me as his friend.I was so hurt ,of all people.I didn't do anything bad.In fact,that was great because I am proud of him.