If you don't get any answers here, you should try smartbitchestrashybooks.  They often do "do you know this book", you just need to email Sarah or Candy.  They have such a large following someone almost always comes up with the title.  Good luck.

I remember a couple of books with this name, but no harlequins since I don't read them.  The ones that come to mind are Devil Takes a Bride (Foley) and Then Came You (Kleypas).  Both were very good and keepers for me.  Don't specifically remember the library thing, though.

I think I read it too and I can't think of the name.  It sounds very familiar.  Post if you come up with the title.

This is totally from left wing here, but is it "Merry's Christmas"?

I think I may have found it. Somebody on another site suggested  Belle of Portman Square by Clarice Peters. The cover seems familiar, and so does the story. I'm waiting for it to get here to see if this is really it. I'll keep y'all posted. Thanks for all of the suggestions!