Ride the Thunder by Janet Dailey

 He's Brig McCord (no really), a Hatchet-scenario survivor, ex-soldier of fortune, and rancher.  She's Johanna something or other, hot redhead-in-certain-lights and general doer of nothing in particular (except for, of course, big game hunting with her dad.)  It's a tale of murder, mystery, and doing it - it's Ride the Thunder by Janet Dailey! Content warnings for this include big game trophy hunting which is super gross, including some skinning and stuff, mild ravishing, a guy who's just an asshole to women including sex workers and anybody over the age of 25, and a father daughter relationship that doesn't seem to be incestuous or anything but it just kind of pings your Bad Dad radar.  Oh and of course murdering murder.  On the other hand, anti-content-warnings: no horses die and there's a gay character who isn't evil or funny, comes out in a nice scene to his sister, and then does not die.