Constancy – Quality of being unchanging/faithful
She was constantly at sea (constancy). Even if you pleaded with her to come on to land, she was unchanging and faithful to the sea.
Examples of constancy in a sentence
Thanks to his constancy, Keith is the kind of guy that everyone loves for being dependable.
I wish I could say my sister was known for her constancy, but she rarely keeps her promises.
The constancy of my friend Marge makes me feel that I can always count on her, no matter what.