Why won't I get wet?

So, I've been having sex and it's been so so good. I love lube and it's not a problem but we always use it because his dick won't fit and it hurts him if we don't. That makes me feel bad! It's because I'm not wet enough I presume and I just don't know why. I'm really turned on and everything but theres just not enough there. Is there something wrong with me? Is this something I can change?