I can relate to this. I don't have it figured out yet, but here are my thoughts.
It comes down to your inner game. What are your true core beliefs about women in your life.
You've got to get to the point where you realize that everything you get from women in terms of happiness and fulfillment is temporary. They CANNOT bring your life everlasting happiness or contenment. They simply can't. No way, no how. I don't care how perfect you are or how valuable you are to women, they all will eventually disappointment if you're looking for your identity or a way to enjoy or be at peace with life through them.
Up until I was about 19-20 years old, EVERYTHING I did was geared towards this future I had always envisioned for myself: A good job, a wife and some kids. To me that was what life was all about. So everything I did was aimed towards creating that reality for myself. There wasn't much ambition, risk taking, creativity, imagination, or real pleasure in my life. I just wanted a girl to like me, to care about me. I wanted a girl who I could be MYSELF with. I didn't want to have to put on an act. I wanted that gooey, warm "It's all going to work out just fine" feeling and I was looking for it in women. I was trying to recreate that warm feeling I had around my Mom and Dad as a kid. You know that feeling, that feeling of being able to just relax and not care and basically receive love and care without having to put out any effort.
But I've come to find out that this is impossible to do through women. You literally can't do it. No matter how perfect or valuable you are to a woman, they will all disspointment you in some way if you try to find your identity, peace of mind, happiness or purpose in life through them. Doing otherwise causes guys to settle for things in life they wouldn't otherwise because they can always fall back on that warm, gooey feeling of finding true love some day, finding some woman who will love them forever, without question always. Your expectations of them, and people both men and women in general, are too high if you expect other people to fill that void for you. They cannot do it. As men, we have to have a firm foundation for our life. A career you're truly interested in, a hobby or two you really like, an overall meaning to your life that will always be your rock.
Once you have that, and once you truly see women for what they are, all this nervousness and insecurity about holding and maintaining an LTR will be gone. The guys who do the best with women and who, ironically, are able to maintain long term, fulfilling relationships with women are those who truly are OK with the fact that she could be gone at any moment. This doesn't mean they don't love her, care for her and do nice things for her, it just means that she is not his rock in life. She is not his foundation. Women SAY they want that from a man. "I want to be his everything". But the fact of the matter is that this is not a natural state for a woman OR a man. A woman wants to HELP a man on his mission in life. She wants to make him better. He in turn wants to care for her and protect her.
^Notice how different that dynamic is from A-LOT of relationships you see today? That's why guys f*ck up on first dates, become needy after sex, text too much, etc. You're looking for a meaning for your life within some woman who you barely know. You're looking for your identity within her and a purpose for yourself. Of course you're f*cking up when you think that's ALL on the line with these women. But it's not. And it will never be no matter how much you think it is. You can start living in reality and do the hard work necessary to build a strong foundation NOW or you can take the easy route, that millions of men before you and after you will, and throw your hopes and dreams into women and pray that it turns out OK. You've basically got a 50/50 shot.