A Shot In The Dark (Help Me Remember This Book?)

Lately, I’ve been remembering books that I’ve read when I was younger, and as always whenever I thought of such things, one always came back to haunt me, because I had lost this book somewhere. I remember liking it because I didn’t expect to like it (I bought it in a bookshop in a mainland airport on a whim for a flight).
It was a fantasy/sci-fi book.
In it, there were these people who (I believe) lived in an apartment complex, and in the middle of the complex there was a garden-like area with a door/wall on a small hill.
Now, it turns out there was a race of magical cats in this book, the door was a doorway to their world. They could turn human, but they had distinguishing characteristics that could give them away, such as bigger ears than normal, or some other sort of out of the ordinary physical ‘tell’.
Otherwise, I don’t remember much at all. I remember that a guy from the book went into their world and ended up falling in love with their queen, but I can’t remember if he had to save the world in that book.
I know, extremely vague overall, but I tried a broad Google search that came up empty.
So I was hoping maybe a Doper out there could have possibly read or heard of the same book?

EDIT: Oh yeah, and one part of the book discusses how, and I’m paraphrasing, “You know how cats always seem to disappear but eventually just turn right back up out of nowhere?” I think it had something to do with how they’d go invisible. Or maybe it was a time-skip. Or going back to their world. Aargh! :smack:

The Catswold Portal?