Hearts on Fire by Amber Thielman

Becoming the first female firefighter in the small town of Lakewood, Washington's department should be something to be proud of, but Hallie Harper has never felt so rejected. 
The men don't want her there, and neither does anyone else. 
Fortunately, Hallie has someone on her side: their captain, Tate Becker. 
Handsome, kind, and charming, Hallie isn't sure she'd make it there without Tate's support. 
As Hallie fights for acceptance into this testosterone-riddled, tight-knit crew—she finds that the only person she wants to be around anymore is Tate. 
Too bad she's engaged, and he's dating another department's jealous paramedic.
Just as she's fitting in, the squad finds that a hidden arsonist is starting these fires...and it could be one of their very own.
Hallie is framed, and trust shatters. 
Someone wants her gone. 
Proving her innocence and getting her crew to trust her again means finding the real culprit, even if it kills her.
Fire isn't the only thing heating up this department, and time is running out; possibly for all of them.