Too funny..I've been on the receiving end of this. My FWB, "Meliss" (name change) hates being home with her idiot husband, and makes up various excuses to be gone for hours and fuck me. The gym is a common one, since her body is five kinds of perfect, anything with her car, or, pulling more hours at the nursing home where she works. She met me at my usual sports bar a few weeks ago, and came in looking more than her usual fantastic; All done up, tight jeans in the leather boots, long nails done, and looking like a fashion plate.
Give me a hug and nice kiss, and sat down, her right hand on my leg. "I'm at the gym, by the way..Don't I look good?" she laughed, referring to what she told him. We had an appetizer and two drinks, then back to my house for an evening of intense fucking and pleasuring one another. And the guy knows nothing.