Your guy secretly makes his money stripping and doing private parties but nobody in his life knows it. His wife/girlfriend mistakenly believes he does something more tame or mundane, maybe a bartender or mechanic. She wouldn't want to know he's taking his clothes off for other people and definitely not about the touching and things that go on at the parties.
At his latest gig though, her friend or sister is there and both end up surprised to see the other. He has to get paid though so rather than explain, he performs...And while performing, since some fun is expected, he works his way between her legs to go down on her, partially for show but hopefully to keep her from saying anything. Before all is said and done though, he ends up inside her and crosses a whole bunch of lines, personal and professional.
This could lead to an ongoing infidelity line with possible pregnancy scares and whatnot.
Other options would also include a slash aspect where he ends up hooking up with a gay friend at a party for cash or blackmail, or a combination of male and female clients that his wife/girlfriend doesn't know about.
If you're still reading and any of this interests you, let me know what face you'd like to use and one of us can set up custom to discuss further. Also ignore the face if you want, we can discuss the face I use as well.