  A suggested model for quasi--periodic eruptions (QPEs) from galaxy nuclei
invokes a white dwarf in an eccentric orbit about the central massive black
hole. I point out that the extreme mass ratio allows the presence of strong
Lindblad resonances in the accretion disc. These are important for the
stability of mass transfer, and may trigger the eruptions themselves by rapidly
transferring angular momentum from the accretion disc (which is likely to be
eccentric itself) to the orbiting WD companion at pericentre. I consider the
effects of von Zeipel--Lidov--Kozai (ZLK) cycles caused by a perturber on a
more distant orbit about the central black hole. I show that ZLK cycles can
change the orbital periods of QPE systems on timescales much shorter than the
mass transfer time, as seen in ASASSN-14ko, and produce correlated short--term
variations of their mass transfer rates and orbital periods, as recently
observed in GSN~069. Further monitoring of these sources should constrain the
parameters of any perturbing companions. This in turn may constrain the nature
of the events creating QPE systems, and perhaps give major insights into how
the central black holes in low--mass galaxies are able to grow.
