1. Unrealistic standards of perfection from their potential mate. I think some women do this on an unconscious level to self-sabotage. It's the only viable explanation.
2. Poor communication. You would not believe how often a woman stops texting or calling or connecting with me in any real way and then later makes it sound like I started ignoring her. I've learned to cut those kinds off ASAP.
2.5. (ties in with communication) Why do so many woman feel that the best way to tell a guy they are no longer interested in dating him is to just start ignoring him completely? Then when he reaches out thinking things are still on, she leads him on instead of telling the truth?
Seriously people, when it comes to dating, it's perfectly okay to tell someone, "Hey, I like you, but I don't feel that connection. I wish you luck. Goodbye."
It's not a breakup! We aren't going to break down and cry, or beg you to take us back. We went on 1 or 2 dates!! Rejection at this point is fine (if it's done respectfully). We've invested both time and money in you, so please just be honest with us and we will respectfully oblige and move on to someone else.
The dismissive "hope-they-get-the-hint" method is horribly mean and if you do this to people, you are an apathetic douche supreme.
3. Talking about, and comparing me to, their ex. Every new person is just that, a NEW person. They should always get the benefit of the doubt and a clean slate.