I was going to do an online search to the letter because my take was completely different. I see Amberlee beat me to it. The issue was his cats are messy, and she does not want to put up with it. That's a difficult thing for some cat lovers to put up with, much less someone who does not even like cats (although she does not specifically say she doesn't).

That being said, they are not even married and are already in counseling (I've never understood that concept - if you can't get along, BREAK UP! What have you invested in dating that would compare to a marriage? But I digress!) so I agree with Amberlee that the cats are just a symptom of a deeper problem. And that being said, I think the deeper problem is that the boyfriend is a slob, and she doesn't want to put the blame on him because then she would be forced to confront some deeper issues - such as that they may not be compatible at all.

But, I still didn't like Ann's flip answer.

His answer will tell you everything you need to know.
I don't know, somehow that sounded to me like the guy is a 'baddie' should he choose his cats over the girlfriend.