I'm a huge fan of Doc Love's dating advice and I think there's volumes to be said about a woman's interest level. If the relationship is going nowhere fast, than she'll get bored and begin to look at the grass that is greener.
I'm a firm believer that "once you're out, you're out" Don't try to stick around and do the friendship tip, that will only hurt and gruel the emotions more when another man is in the picture. It's better to keep our mind's clear and intent on meeting new people that can benefit our lives.
There are so many factors that can go wrong in a relationship, maybe she was not at a point in her life to seriously commit to a man because she was still trying to figure herself out and what she wanted from life. Being wrapped up in a relationship can put smoke and mirrors in front of us that cloud life's reality.
Instead of worrying about what failed, study and become a master of don juan's philosophy and keep improving yourself.
If you focus on becoming a better man, you'll eleviate most the problems that lowerered her interest level in you in the first place. You'll find a woman that is more attracted to you now than when she first previously walked by you - think about it. As you improve, so do your options do in the dating realm.
If I were to go back and ask all my previous ex's they'd probably tell the interviewer nearly identical reasons why she dropped me.
Anwers like
"He's too needy"
"He's not confident enough for me"
"I couldn't trust him to protect and take care of me"
"He's too available"
"He wasn't a challenge, I had nothing to pursue"
"He said 'I love you' so soon when he hardly even knew me" etc...
The truth may hurt? Probably, but I know now thanks to DJing what women are attracted to, and can easily spot out my insecurities do my best to remove my returning AFC ways when they reveal themselves.
If you can learn to use your observing ego to ask yourself questions like "do my actions increase her interest level or lower it" than you'll have an easier time in dating.
Here's a little NLP for you. If you must FIND OUT where you messed up in the relationship, play back the old tapes of memories in your mind when she began to withdraw affection, time, and appreciation towards you than parell it to your actions and you'll see where you messed up. Woman don't dump a guy over night. What you couldn't see is that she began to withdraw a long time ago through subtle actions.
Keep your head high on your shoulders and forgive the past mistakes you may have made. Just don't forget there's
5 billion people on this planet. The beautiful thing about a new relationship is that you get a clean slate. Hopefully you've learned more about yourself in reflection in between relationships to know more about yourself and what to do better next time.