I don't think there needs to be sex for a relationship to be fulfilling - virgin or not.
I am not a virgin. I have sex with my boyfriend. However, my girlfriend and I, almost never have sex. At first this worried me, not because either felt any less romantic with one another but because sex is generally expected and some would say that, without it, what we have is just friendship.
It's not. We've been together about 9 months now and we're happy, affectionate and in love.
I do agree with insane mystic though. If we didn't both have other partners whom we were sexual with, we would probably have sex pretty regularly, but as it is, that need is pretty much covered for both of us and we prefer to be intimate in other ways.
Also, as for your original post stating that in your readings you've found that polyamory is very much focused on sex - I would say that's not true. Sex in poly is no more of a focus that sex in monogamous relationships. In fact, I've found that from my experience on this forums, poly people tend to be less focused an just sex and more focused on the closeness and love they can form with another.