Mate, you're a mess. And you don't get it. In your fourth decade you'd want to figure it out quick!
First off - the "bad boy" thing. Women love a bad boy not because they're an arsehole per se. It's more the thrill of the occasional time he's nice to the girl. Got it?
Okay, I'll put it more simply. Dudes a fucken POS to everyone and anyone. Occasionally he flickers on the nice switch to the girl involved, and she flips. She's just done what everyone else can't! She's got the jerkoff / buttmunch / asshole to do what he never does - and be a nice normal human being! {Albeit briefly}.
The next challenge then becomes to keep the nice version around for the majority of the time. He doesn't - she redoubles her efforts. He flickers to nice briefly...this can go on for years.
Second off - "You date the wrong sort of girls for you". You mean you date a set of active and dormant personality problems and wonder why it doesn't work out right?
I think you imagine yourself as some sort of horse riding prince, scooping up women at a low personal and emotional ebb and being the knight in shining armour. Then after you've come to the rescue, and helped the girl realise what an amazing and unique person she is she should be grateful and want to spend the rest of her life with you right?
IT DOESN'T WORK LIKE THAT.
If you want to help people out of the gutter - fine. You can be a good friend. A father figure. A mentor. A life coach. A big brother.
You're not boyfriend material! You're somebody who helped somebody out at a low point, and got them to the point they have recovered and can move on.
Hint - they're not going to move on with you!
When people help us when we're incapable of helping ourselves, we don't fall blindly in love! We feel grateful - and oh so embarassed for the mess we were in - and then we take our new selves and find an equal.
So thirdly mate - stop looking for fallen stars, or wondering how some sociopathic prick is never on his own. Do the things you enjoy, that make you happy, and that aren't destructive to your self or others. Go and be the best person you can be on your own, and you'll have an existence where you're happy, content and fufilled. You know what happens next? People see you as this content, happy person and realise you've got something going for you. You've got an existence that they like and would like to be a part of.
Better than that, they're not a set of active personality problems. They're someone who sees you loving what you do and doing what you love and want to be part of it. Not a fallen angel - an equal!
It's really not rocket science. Helping tragic cases, or trying to be something you're not has got you to where you are today. Do something different and make yourself happy. When you're happy the rest comes along with it.
Don't take my word for it. There's a couple of billion people who've done the same thing. This is the best advice you'll ever get mate. Hope you act on it before your fifth or sixth decade!