Doing The Intern (Third Wheel Series 1, Book 1)

He walks into the large office area, eyes wide and staring and heart pounding. A big hand comes down on his shoulder; he glances around. Wow... Two steely gray eyes inspect him - up, down, up, down: They sexualize him; caress and seduce him. The intern shuffles about. This man and his partner are about to turn his world upside down. The intern's job has just begun!

This is the first book in this series. You can find all four in the Third Wheel Collection 1.