Here are 3 examples of what happens when they exhibit poor behavior and you cut them off:
1. Dated this girl for several weeks. Nothing serious. She showed up at a bar I was at one night way later than she said she would arrive. She arrives about the time I told her I was originally leaving. When she arrived she gets mad because I refused to pay for her drink. I had things to do in the morning and she had no concern about what was important to me. When I told her I was leaving she started insulting me. For the next 6wks I get random texts/calls from her begging to see me again, how great I was, and that she was sorry for her poor behavior. Not once did I reply to any of it. Even got a few nude pics trying to suck me back in.
2. Had another girl this past summer that neglected to tell me about a son she had after 2months of dating. She left her son behind at the age of 16 shortly after the father died. This totally goes against my value system. I refuse to surround myself around people who do things like this. I tried to better understand it, and she grew more angry. I told her she should leave. For several weeks she texts me apologies and I didn't respond to any of it.
2. I had a live in gf of 2yrs acting up, being overly dramatic, bitchy, etc. I got tired of it and told her she needed to move out and go work on herself. We could still talk but I was done dating. I cared a lot for her and saw a lot of potential and good things in her. But there was nothing else I could do to that would convince her i wasn't playing around anymore. Me kicking her out got her attention. She started reading self help books, went to counseling twice a week and made a lot of progress. After I was convinced she had improved, we started dating again and she eventually moved back in with me. Things were much better this go around. She took me seriously this time and gained a ton of respect for me.
Figure out what you will and won't tolerate. Keep your side of the street clean. Stand your ground. Draw the line in the sand and walk when you feel violated. There is a time and a place to sit down and discuss issues, but very few women respond well to this. Most of them need to see the hammer drop and you withdrawing before they take notice. And some things shouldn't even be discussed.