My wife and I seem to be in sync here. Both our drives have been up and down due to external pressures (work, parenting etc...) but when they're at opposite ends, it's no big deal. I guess our drives are moderate, and the rest of our relationship solid enough, that we can accept a dry spell for what it is and comfortably look forward to the coming deluge.
Our frequency has definitely slowed over the years, but our intensity is much, much stronger.