Tension comes from lack of communication. Notice how you're not talking with her about how there's tension there? Instead you bring it here for advice.
I know this isn't very <i>male</i> of me, but you should have a coversation with her about this. "Hey, I'm noticing it's a little different between us lately. I'm feeling some fairly interesting ways about you recently, and I don't know what to make of it or what to do about it. What do you think?"
She'll respect you for being honest with her. Then, if you're lucky, she'll fuck you silly.
