Eleanor Roosevelt wrote:
If someone betrays you once, it is his fault; if he betrays you twice, it is your fault. Many people will walk in and out of your life, but only true friends will leave footprints in your heart. To handle yourself, use your head; to handle others, use your heart. Great minds discuss ideas; Average minds discuss events; Small minds discuss people. Learn from the mistakes of others. You can't live long enough to make them all yourself.