for the women I've known, who are all stronger than they know

I often wonder why women continually go for the same type of man.
Why women will constantly put themselves on the line for a man who treats them, if not like dirt, then not nearly as good as they deserve to be treated. It's often the women who dream of the fairytale, the knight in shining armor, that seem to get wrapped up with a guy about as far from that ideal as is possible. I see it again and again, and they tell me about the guy, and how they don't really know why they're attracted (addicted?) to him. I've seen it, and I've been there.
It's so easy to get wrapped up in...because they always give you just enough hope that they may change that you don't want to give up on them or the relationship. "He's trying". God if I had a nickel for the every time I've heard (and said) that one... The bottom line is this: Men don't change unless they WANT to...and no woman can make a man want to change. The only way a man will change is if he believes it is in his best interest. At least until the relationship is seriously committed, then I can't really say because I haven't been in a seriously committed and (this is key) functioning relationship before this one.
It's so easy to see how messed up a relationship is from the outside...but when you're involved...well, it's hard to see the forest for all the trees. I've had friends who have been in relationships with absolute dicks for several years on again off again and they're miserable for so much of the time, and it seems like such a waste to me. I give them support and tell them they deserve better, and they always do the same thing: nod sadly and say "I know..." trailing off at the end, which means the same thing: "I know, but....". There are any number of options for what "but" can mean...unfortunately, the "but" means they aren't ready make the change. I've learned the best thing to do is to be there to listen and encourage and just support unconditionally until they feel they're done with whatever it is.
I've had friends ask me before if I get sick of hearing about so-and-so with their messed up relationship. I really don't. I know how important it is to have someone you can confide in and who will support you and be there to lean on without getting irritated. I just keep hoping that one day these women will understand their worth, and will realize the only way the guy will understand it is to tell him to fuck off until he can be a man, and, most importantly, be able to stick to that statement knowing they deserve a loving, caring, (relatively) stress-free relationship.