Coveting?

I wonder if it's innate, a part of human nature, or if it's something that gets attached via nature or nurture to only a few specific human beings: the desire for what we can't have. If this can really be called coveting then I suppose every person experiences it at some point. There's a Commandment about it, after all. But for me, and for certain people I know and care deeply about, wanting what we can't have seems to be a chronic condition.

I kind of wonder if I'm really that covetous though. I don't want something just because another person has it. It isn't a matter of competition for me. It's a matter of personal fulfillment, or even validation, I suppose. Is it foolish of me to feel that I deserve some of the most important things I want in my life - a wife, a family, true friendships, joy and satisfaction in my work, for example? I have hints of some of these things, but somehow, I always either manage to screw them up, or whiff through them, like a ghost, clutching on, trying to take hold, but slipping past like I wasn't even there.

My life seems to be going through an extensive period of "fulfillment Ping Pong" - that is, over the course of a year, or a month, or a week, or even, often, within a day, I go from experiences that are fulfilling and satisfying, to experiences that depress or discourage me, times of emptiness and pessimistic speculation. At these times I can't help but wonder about whether all my relationships will fizzle; if all my work will be for nothing; the possibility that I will continue, unnoticed and taken advantage of, until I despair.

In other words, it may be envious or jealous or covetous of me to say, but....do I ever get a chance to be mostly happy all the time?