Thanks all for the replies. Just to clarify some things:

I don't have fear of the bedroom; I have fear of closeness. I tend to feel suffocated when I let somebody become too close without having either other people or my own isolation to fall back to. I also feel like having more than one partner makes more logical sense because of reasoning similar to investing strategies. Would you invest all of your money into the stock market without any certainty that you would make a solid ROI and risk losing everything? I doubt it. Similarly, I don't want to dump all of my emotional energy into one person and risk abandonment later on down the road without contingencies in place to protect myself.

My reasoning for being this way doesn't directly pertain to sex. In fact, if I truly like somebody, I'll generally keep them in my life without involving sex. My reasons for getting bored with people don't involve sex so much as a combination of burn out and being fiercely independent by nature.

Ultimately, it's my choice who I let in my life and who I kick out of it. I'm extremely careful as to who I let close to me because as far as I'm concerned, all but the rare individual who would accept me despite my problems and faults or how different I am to most is expendable to me.

P.S I've accepted that living this kind of life has the potential to make me lonely later down the road. I've already told myself that if I ever get to the point to where I'm too sick to care for myself and there is no way of curing my illness, I would rather kill myself than to suffer and be at the mercy of others.