We all get busy David, but you can tell when somebody is making an effort and someone isn't. If I'm busy and I'm interested in someone I'd probably take 30 seconds and send a quick note to say I'm swamped today, but I will write you when I have a moment, whatever I can do to very quickly let them know that they are on my mind. That small gesture is usually enough for somebody to feel important. How often have you been really interested in someone and disappeared on them or given them nothing to work with?