This book is on pre-order until book delivery arrives. 
 
Incomplete Strangers (Wilder Hearts #2) by Laura Elise Bishop:
 
On the surface, Molly seems to have the perfect life. She’s got a dream job, great friends and a sister who adores her. Deep down, she’s afraid, and lonely. Taking care of everyone else ensures she doesn’t have to think too closely about what’s missing from her life and the secret she’s keeping - that the smile that she exchanges with a handsome stranger on the train is the best part of her day.

After landing his dream job, Chris is adjusting to moving back to the city he grew up in, and a long commute. He’s always been the one that people turn to, but when he finds the fast pace of his job and city life hard, he struggles to open up. He finds solace in the smile of the beautiful blonde woman on his train, but he can’t seem to work up the courage to talk to her.

After a traumatic incident, Molly’s return to the commute is disrupted when the train is plunged into darkness. It isn’t the armrest she grips in fear though; it’s the arm of the handsome stranger next to her.