At first spite
(Book)

"After her fiancé's brother convinces him to break up with her before the wedding, Athena Greydon moves into a ten-foot-wide Spite House between the two and engages in some well-deserved payback"--,Provided by publisher.

"When Athena Greydon's fiancé ends their engagement, she has no choice but to move into the Spite House she recklessly bought him as a wedding gift. This is a problem, for several reasons: The house, originally built as a brick middle finger to the neighbors, is only ten feet wide. Her ex's home is attached to hers. And Dr. Matthew Vine the Freaking Third (aka the uptight, judgmental jerk who convinced his younger brother to leave her) is living on the other side, only a four-foot alley away. If she has to see Matthew every time she looks out her windows, she might as well have some fun with the situation--by, say, playing erotic audiobooks at top volume with the windows open. A woman living in a Spite House is basically obligated to get petty payback however she can, right? Unfortunately, loathing Matthew proves more difficult than anticipated. He helps her move. He listens. And he's kind of...hot? Dammit"--,Provided by publisher.