A difference in appetite is not a sign that something is broken. It is the ordinary state of two different people. What causes damage is the story each person tells about it in silence.
The two stories
The higher-desire partner usually concludes they are unwanted. The lower-desire partner usually concludes they are a disappointment. Both are wrong, and both harden with time.
Separate the ask from the act
A lot of the hurt is not about sex but about being turned down. "Not tonight, but I want to — Friday?" costs nothing and lands completely differently from a flat no.
Stop keeping score
Counting is corrosive. If you are tracking the number, the conversation you need to have is already overdue.
Aim for a rhythm, not a number
Most couples who resolve this do not land on a frequency. They land on a way of asking and refusing that neither of them dreads.