Two Thieves in Deadwood: A Clean Western Mail Order Bride Romance (Brides of the Gold Rush #4)
Ellie Gracen

This is a stand-alone story. You don't have to read the series in order.
Delilah lost her husband when a hired hand robbed and shot him. Unable to get justice, she's left alone and lonely with no livelihood. She misses her husband dearly and is struggling to survive in this harsh gold rush town with little left.
John and two of his associates are waiting in the dark to rob a carriage. As they escape with the gold from the carriage, a strange thief sweeps in and takes it. The group of thieves are completely baffled on how someone managed upstage them and get their gold.
John later encounters Delilah and believes he might have found the strange thief. Bent on getting his gold back, he tracks her down. Angry, frustrated, and unable to intimidate her, he is enthralled with Delilah's inner strength and character.
John schemes to help her get that overdue justice and get his gold back at the same time, but he's not exactly clear what his motivation really is. Something has come over him, and the gold seems to lose its luster next to Delilah.
These too thieves may get more than gold in the process.
Read the rest of the series:
More Precious than Gold.
Finer Than Gold.