To 1:
It is very important for you to explore why this is happening. You should either ask some trusted friends if they can be honest with you and tell you if there is something they see that may be turning off the girls you date. Or find a dating coach or therapist to help you explore what it is.
Sometimes what is turning off a dating partner, may be detrimental to a marriage. Find out what it is. If you know what it is, and think that anyway nobody is perfect (the way you ask your question may be an indication of something like it), that is the wrong attitude. Fix it. And not only for while you date. But it should be a genuine desire to change.
I do realize that it could be you are not doing anything wrong. And the right one just hasn’t appeared yet. But be smart and see if perhaps you can get some feedback from someone objective to let you know if there is some change that needs to be made.