Dependence and vulnerability

For years I felt limited, unable to do all the things I wanted, unable to be the person I wanted to be. I don't know why I thought at the time that the relationship I was limited by offered more good stuff than bad, but at least I saw the light at some point.

Ever since I have fiercely been safeguarding my independence. It has become my most valued possession, not to be taken away by anyone. Relationships I have been in over the past fifteen months have allowed me a great degree of independence (while being monogomous, of course), and I would not have it any other way. The moment I feel unable to do the things I want to do, the things that make me happy, and which make me who I am, that's the end of it. Fortunately there are girls who understand this. As it stands, I am very happy in my current relationship, and I've got the best of both worlds: a great girlfriend (who also values her independence), and independence and freedom at the same time.

Even so, one part of being in a happy relationship scares me: the more you love someone, the more difficult it is for you if you lose that person. And being afraid of losing someone makes you vulnerable. Of course, when you're young there is a far greater chance of losing a girlfriend (or boyfriend) because she breaks up with you than losing her because she dies of disease or gets killed in an accident, but it is losing your partner, nonetheless, possibly a great shock.
Last year, my aunt died of cancer. She had been married to my uncle for decades and the man was devastated by her death. Losing her sort of meant his world ended, I guess. I don't know for sure because I haven't even spoken to him since then. However, I hear he spends a lot of time alone and hardly wants to see any people now, so I think it a safe bet that he is truly devastated by the loss. The idea that my life would be 'ruined' by losing one person makes me extremely anxious. It means I would be incredibly vulnerable, and I don't want to be dependent on anyone.

This got me thinking: will I ever settle down with a woman, buy a house together and have kids and all that, or will I be too scared of my resulting vulnerability and dependence? Suppose I had two children and a wife: I would then have tripled the chances of becoming an emotional wreck if some drunken asswipe killed one of them with his car. I am not one to be guided by fear, as that normally takes away a lot of fun from your life, but being dependant on (the well-being of) one person is something that does scare me.
It is like I need to know for myself that I could do without my chosen partner if I had to, for whatever reason, as a means of self-protection or something. Sure, I am able to be in a loving relationship, but it is like I am always prepared for it to end, so I will not be devastated by it if it suddenly does, like my uncle was.
In other words: investing too much in one person out of all the billions of people in this world seems like too great a risk. Just like investing all your money in the stock of only one company is: if that one company suddenly goes bankrupt, you are done for.

Am I seriously comparing women to stocks here? That is not the image I was aiming for ;) but being a careful investor seems to have common ground with being a careful lover, nevertheless. Not too romantic, indeed, but perhaps it is better to aim wide, instead of focusing on this narrow corridor with closed door upon closed door mocking your chosen route in life, even though you may be walking on red carpet for a while?