my question is how is the rest of your relationship? Honestly is the naming of one's pet really something to create issue with? Now if he purposely named the cat in that way based on the ex, sure I'd say something MIGHT be up, but first off, you suggested the name, he didn't realize initially why it was natural to call the cat that particular name so no ulterior motive is involved at all. His realization was after the fact. Unless you don't believe him and if that's the case, there are deeper issues going on than the naming of the cat and this event only brought that issue out.

So I would ask yourself whether this is really an issue in the grand scheme of things and if this is that big of a deal to you, I'm going to guess that everything else isn't necessarily hunky dory. But if they are, you may be splitting hairs.