A little background is needed here. This girl and I have known each other for years. We have always been flirty with each other, but neither has tried to escalate. In recent years, I've heard talk from mutual friends that she thought I was very attractive. I'm now to the point where I want to escalate, but do so in a manner not seeming desperate. We text sometimes, but there are times, like today, that she doesnt reply. Is she trying to play hard to get? How do I heat things up with her?