I think that with women, it's because they often feel too vulnerable when someone touches them. It's a puzzling thing to wonder what makes someone more or less affectionate. I can't comment much on what that shows up as for men since I'm not one, and the rules are pretty different between sexes. It always makes me a little sad that I can't 'be myself' and give someone a hug or sit close or even accidentally brush them without being worried that I'm offending them or making them uncomfortable, so it's a real relief when I meet someone who is also affectionate naturally (currently I have only one friend who is like that.). Who out there is like that or knows people who are? What do you think of it? It's hard for me to imagine why it's such a horrifying thing for some people unless they've had a traumatic experience. Otherwise they have a huge personal bubble, and make sure everyone knows that upfront.
sometimes they'll muster a hug because of cultural expectations, but that's about it (and it's awkward). Many of my friends are really uncomfortable with being touched in any way.
I am a female and straight, but I like to hug my friends, even hold hands or generally be ok with physical displays of affection. So, this may be a regional thing, but I find that so many women that I meet don't like to be touched at all (well, unless it's intimate, I guess?).
