Thank you for sharing your experiences. They were quote eye opening. However, like another commenter noted, I do not believe starting and ending relationships is a helpful practice in learning about people. People will be people and they will keep surprising you. You have to learn how to cope with yourself and accept that others may disappoint or hurt you. Likewise they could also be fantastic to you. Treating people like some form of disposable commodity to try out for a period and discard may ultimately be harmful to developing deep, long term friendships.