These word can be such as zeal, zest, zatch, zany, and zealous. "Zatch" is a term for a female genitalia, so you probably do not want to use that when explaining your irrevocable zest for said person.
A space word that starts with z is Zaurak.
Another word for a blimp that starts with a Z is a Zeppelin
zenith is a complementary word that starts with z. It means on the top, or the best.
zestfully
honest
Zucchini is one word. It begins with z.
enchantingexquisite
Vows are romantic words. The word begins with the letter v.
science words that starts with a
zero
zèbre
Seize.