There is always name of female before male like Siya Ram, Radheshyam then we say Shiv Parvati not Parvati Shiv.
I don't think that there are any such strict rules. As a proof, see the verse given below.
LakshminArAyanau vAnidhAtArau girijAshivau |
Srigurum gurupatnincha pitarAviti chintayet ||
Guru and Guru's consort (Gurupatni) should be thought of as one's own parents. They are to be thought of as Lakshmi-NArAyana, VAni-BrahmA, GirijA-Shiva.
KulArnava Tantram 12.35.
Note that here GirijA is a name of Goddess PArvati. So, seemingly there is no such rule like we should only say Shiva-PArvati and not PArvati-Shiva.