That's a day negative 10 deal breaker. I can be casual friends with a "witch", but being in a relationship means I have to pretend I believe that stuff, and no one can keep up an act that long.
It's as fake as any religion. I mean it is kinda one, I think. I have very little awareness of it, I'm pretty sure witches and wiccans are different, but it's all beyond baloney, so I don't really care about the subtleties.
I mean... You don't have to believe someone else's beliefs to be in a relationship with them. It happens all the time. I work with a "witch" and she's like every other normal religious person. Wears a necklace, has a thing on her door, goes to work...
If you want to believe that belief in external reality to your senses requires a similar leap of faith that belief in unprovably extant supreme beings requires that's fine, but that's not what the word atheist means. That's not how people use it. They don't use it to refer to people who refuse to believe in things requiring faith (as in believing in something that can't be proven). It is used to refer to people who don't believe in gods.