This won't end well
(Book)

"No new people: that's Annie Mercer's vow. It's bad enough that her boss sabotaged her chemistry career and her best friend tried to cure her with crystals. But after her fiancé, Jon, asks for space while he's gallivanting around Paris, Annie moves in with her mother in East Haven, Michigan, and decides she needs space too--from everyone. Yet when Harper moves in next door, Annie can't help but train a watchful eye on the glamorous but fragile young woman. And if keeping Harper safe requires teaming up with Mo, a maddeningly optimistic amateur detective, who is she to mind her own business? Soon Annie has let not one but two new people into her life. Then Jon reappears--and he wants her to join him in France. She's pretty sure letting anyone get close won't end well. So she must decide: Is another shot at happiness worth the risk?"--,adapted from back cover.