Yes I feel incredibly lonely a lot of the time. I'm an introvert, which I define as recharging myself through quiet times at home (note at bottom about this). I've also had few friends throughout my life because of frequent moves, and I'm not especially close to my family (both parents have passed on and my siblings aren't my age). So spending a lot of time on my own is not new to me. Sometimes I'm fine with my social lackings, other times I feel a crushing loneliness that I can hardly bear.
I'm lucky enough to have a DH and 2 wonderful kids, but the loneliness still rears it's head because friends are so hard to find. I work at home so I hardly ever get out, and I live in (worse, I'm an outsider in) a small and tight town, where everyone is outwardly very friendly but most have little use for me beyond a casual acquaintance.
Lately I find the lonliness worse when our pop-culture gets to me. TV (which I rarely watch) and books (which are part of my life) so often seem to focus on unrealistic friendships and relationships. Is this because it's what everyone really wants? fantasizes about? I used to think that *everyone but me* had the life of Friends the TV show. In reality no one (beyond college) has that life. People get so busy with the demands of life an commitments that it gets hard to find the time to cultivate friendships. I feel too like others have already filled their friend quota, and don't need or have time for any more. This makes me feel very lonely.
This quote of Sues: "I've read before that your true life-long, best friends are made by the time you're in high school or college." I don't think it's true but I think it happens a lot. That's because it's a time before the demands of a job, a family, a home, that leave so little time for doing things with other people that lead to good friendships.
Also... I define an introvert as needing to recharge using quiet time, and an extrovert needing to recharge with friends, so I'm disagreeing with candi's quote: (sorry candi ;-))
"Maybe the difference is introvert personalities versus extrovert personalities. I am an extrovert by nature and interface with people all day long on the phone and person. I use a lot of energy doing so. When I get home, I recharge by sharing with DH and reveling in the peace and quiet."
It doesn't matter what you have to do all day, it's what you choose when your battery is down and needs to be charged, so I would call candi an introvert, even though she spends her day with lots of people. I am definately an introvert, but that doesn't mean that I don't need close relationships with others in my life.