I understand how you feel, as I experience the same. I remember being really down and thinking "Damn, if only I could get a hug ,sayingeverything is going to be fine", although it might be a lie, but sometimes lies are necessary!.
And yes, it must have something to do with not knowing how to ask for it, or giving the impression you´re a strong independent person, not sentimental or just cold...so nobody would ever imagine how much a bit of affection would help.
I have no solutions for you, as i wonder myself the same...but at least you´re not alone in that feelings.
A huge virtual hug :)
Btw, I kinda suspect I satisfy a bit my necessity of affection through the virtual world, though it´s absolutely not enough or worse than the real world...do you think it might work that way a bit,guys?