Never a Lawman by Rachel Bird

Love can ruin the perfect getaway…
When Belle LeClair’s US Marshal husband dies, she flees Boston and her wealthy, overbearing mother-in-law–who has already chosen Belle’s next husband! Belle won’t rule out marrying again, but any prospective partner better not have a job that will get him killed.
Sheriff Brady Fontana’s fiancée was murdered on her way to join him in Break Heart, Colorado. Since then, guilt and regret have made him impervious to love. But when he rescues a family of would-be homesteaders attacked by the notorious Deckom gang, one of the sisters shines a light on his cold, locked-down heart.
The last thing Brady deserves is happiness, and he fights his unwelcome feelings for Belle. Which is fine with her, since she’ll never let herself care for another lawman–even one as wonderful as Brady.