Can I offer some tough love? 
I have a friend who has been in counselling because of a broken partner picker, she literally had no idea how to be happy by herself and felt worthless unless she was with someone. This made her easy pickings for the kind of jerks who say all the right things at the beginning and then let out their inner jerk once they have her hooked and then I get phone calls along the lines of “he was so sweet at first what did I do to make him so mad at me???”
Thankfully she’s been making some progress, and she said it was OK to share some things that helped her, so maybe they’ll help you too.
The first thing was to go on what she calls a “man diet” which means she had to break up with her current boyfriend and not date anyone else until her own issues were solved. 5 months and counting now which is a world record for her.
Do not move any deeper into your current relationship, or start any new ones, until you can answer this question honestly: WHY do I date assholes and broken people (to the point where dating someone normal feels wrong and weird?)
People don’t repeat behavoirs unless they get something out of it, so what do YOU get out of dating broken assholes? Do you think you can fix them? Rehab them into being nicer people? Get a thrill from conflict? Feel a need to be punished for something?
In my friend’s case the root cause was an abusive childhood (that I never knew about until she started therapy). Think of Joan Crawford as “Mommy Dearest.” She would go from sweet and loving to physical and verbal abuse at the drop of a hat and was an emotional abuser. Everything bad that happened was my friend’s fault. The jerks were just a continuation of the same pattern, sweet le amour followed by manipulation.
She also admitted she was sort of addicted to the first OMG IM IN LUV! feeling because it was excited and felt good and brings us to
It’s not an either/or thing where you either feel no attraction to the guy but stay with him because he’s decent, or the full tilt OMG HOT SPARKY STUFF. A healthy relationship is somewhere in the middle where the attraction is there but it’s not all about the passion and drama and emotions.
TOUGH LOVE ALERT!
It sounds to me like you’re doing the first, sticking with Mr. Nice because he’s nice but you’re not really attracted to him. That’s not good for either of you, you’ll end up resenting the lack of SPARK and you can’t force yourself to want someone you have no chemistry with. He will pick up on your resentment.
If that’s the case, if you were my friend or my daughter or sister, I’d encourage you to go on your own “man diet” and not date anyone until you’ve gotten your own issues straightened out.
I don’t think anyone can be happy with someone unless they’re happy by themselves first.
You can’t fix broken people.
You can fix yourself. It’s hard and painful and takes a long time but my friend thinks it’s worth it.
Good luck to you. 