How can I learn to be a less judgmental friend?

My best friend and I have been friends for 18 years (since middle school). She is a very educated person but has no common sense. She makes really bad decisions with normal day to day things in particular the men she shows interest in. She meets a man one day, the next day she sleeps with them and then swears to me she is in love and begins talking babies and marriages. All of this before the guy even calls again (which they normally don't). She goes into these situations every 3 to 6 months. In the past I have always been the voice of reason but that has caused conflict in the friendship. How can I learn to be less judgmental? I am trying so hard to be supportive and listen but I get sick of hearing about failed situation after failed situation. She isn't even in relationships with these guys. They use her for sex but she creates these grand love affairs in her mind that never turn out that way. How can I be a friend to her but not hurt her feelings like I have done in the past? I have a family and she claims I don't understand her desires because she is lonely but really I just think she makes poor choices because she needs mental help. What can I do to help her?