My (Not So) Bossy Professor by D. K. Sutton

The straight-ish muscled football coach is off limits.
Detective Liam Mason is fine with that.
Until their arguing and fighting turns to kissing, and Liam can’t get enough.
Trace Powers is the key to their undercover investigation and Liam’s new orders are to do whatever it takes to get close.
But pretending to be a professor and Trace’s fake-boyfriend, even if it’s just for the benefit of his staff, seems especially reckless when Liam discovers an illegal operation happening off the field.
And realizes his feelings for the football coach are very real.
Trace is in danger, and Liam will risk everything to save him.