And now I may have to rename at least one of my main characters.  50 Shades main characters? Christian and Anastasia.  Mine?  Christopher and Anastasia.

Sigh.

I don't know if it's a huge problem since I refer to them as Chris and Ana almost all the time (I have no idea how the 50 Shades characters are typically called, but I'm guessing not that), but it's an uncomfortable and unintentional parallel that I'm not sure I want.

Ouch. That is quite a coincidence. Though I think that, unless you feel it absolutely necessary, you shouldn't have to change your characters names. But if it comes to that, might I suggest you use your shortened version of their names?

'Ana' and 'Chris' seem useable substitutes for the long versions. And that way, you don't have to completely alter them (And nobody will think 'Hey, these names seem awfully close to the ones in 50 Shades of Grey!

Hope that helps.

Yeah, I kind of freaked out at first, but I've calmed down a little now.

I already call them by the short versions so it'll probably be fine.  Still a rather unpleasant surprise.