Caption: A perspective not-to-scale diagram of the Moon's orbit and the lunar node line.
Features:
The line that connects the nodes (and which passes necessarily through the Earth) is called---very imaginatively---the lunar node line.
Note that due to the rotation of the lunar node line, the time to return to a lunar node is shorter than the sidereal month (27.321661554 days: J2000). This period is called draconic month (27.212220815 days: J2000 (see Wikipedia: Lunar month: Cycle lengths). Actually, there are 5 lunar month types and a full understanding of them is rather difficult (see Wikipedia: Lunar month: Types of lunar month).
Why, why must the lunar node line ROTATE?
An exact gravitational two-body system, would NOT exhibit rotation of the node line relative to the observable universe.
But the Earth-Moon system is a gravitational two-body system only to 1st order. So the orbits of Earth and Moon about their mutual center of mass (which is the origin for their free-fall frame: i.e., local approximate inertial frame) are simple only to 1st order.
The Sun and to a much lesser degree the planets add complicated gravitational perturbations to the Earth-Moon system. This results in subtler, complex motions.
We will, of course, not go into the celestial dynamics of those subtle motions. But there seems to be an endless regression of them. Once you've detected and analyzed one, there is another smaller, more subtle one to deal with. Yours truly's patience quickly runs out.
This time frame is called the eclipse season or, as yours truly often says, a nodal algnment---it trips off the tongue.