Paris Apartment

I can't remember when I've been this confused by a book. It started out clear; it was a story of two women, from two different times, one from the past and one from present day. April, the woman of present day, was assigned the task of preparing an abandoned apartment in Paris for auction. In the process she ran across the journal of the woman from the past, Marthe. April is conflicted; her husband has just admitted a marital transgression. She herself has befriended a fascinating Frenchman. Marthe is a courtesan, and the apartment filled with many riches was hers.
Things went along swimmingly for some time and then both Marthe and April do inexplicable things, things that seem random. The entire last section seemed very confused, with all the characters doing inexplicable things, perhaps simply to tie up the loose ends of the story.
This was not an ARC, sadly; it was a fully published book, taken from the shelves of my public library. Was there an editor? Do authors not receive any editing help these days? Do publishers just think people will buy any old thing with a lovely cover and a good start? Did the publisher really read the novel to the end? Very disappointed.