I'm currently writing a 20,000 word contemporary ménage. Very fun so far, but very different from the historicals I'd done. The conflict is driving me crazy.
The thing with a an historical is that there is inherent conflict because of the many restrictions of various times. In a contemporary, a woman can not marry the jerk if she doesn't want to, or she can have an affair with whomever she pleases. There were a lot of rules even 100 years ago to govern that type of behavior.
But always fun ways of working around them!
Luckily, there is plenty of conflict in a threesome, even a contemporary one. No matter how liberal you are, most people don't condone a threesome. I wonder if they think it's because you can't love two people the same way at the same time? Or because people think a ménage is just about sex? Hmm, things to think.