Here's my definition of an erotic couple's photoshoot, or ECP:
A still photography photoshoot where the subjects are two consenting adults over 18 who wish to be photographed while engaged in erotic acts.
Let's not confuse ECPs with erotic boudoir shoots which usually have a single individual as the subject.
I've been doing ECPs for more than a decade and have become rather well known for this service. In my experience, a photographer needs three main skills to do an erotic couple's shoot.
The first skill you need is the technical stuff. Since your subjects are moving, it's a bit like sports photography, but since you are close to your subjects, you can deploy all sorts of creative lighting gear to set the mood you want. The lighting conditions change every few minutes so you need to change camera settings and vary the placement and intensity of the lights without much thought. It's critical that the photographer be able to make the necessary adjustments on the fly, because you need a substantial amount of your mental bandwidth to look for artistic and flattering camera angles. Due to this multi-tasking, it's actually tougher than most sports photography. One analogy would be if you were playing a musical instrument while you were trying to direct the orchestra.
In addition to high level technical skills, the photographer must also be comfortable with human sexuality. Up close and personal as they used to say. Many young photographers find they get flustered when they are around naked people in erotic situations. I know I did back in the day when I first ventured into nude photography.
The final key is being able to interact with people in a way that makes them comfortable, while directing them into positions that make them look their best. Since you are working with real people, not veteran porn actors, you must take their physical and emotional limitations into account. Trying to impose your own erotic preferences on them may not be the best idea. It takes a great deal of sensitivity to understand their desires, which they may have a hard time describing.
Which brings me to another important part of the Erotic Couple's Photoshoot process. I just call it "the interview" in which I ask quite a few questions designed to discover what types of photos will make the clients the happiest. For example, some clients want photos to trade with fellow swingers, some just want to keep them for personal memories. Some want closeups of the intimate parts, some want a gritty porn look and some want a soft boudoir look. Each couple is different and it's important to take enough time before the shoot to get to know them. A face to face meeting before the shoot is very helpful, but I've learned how to conduct the interview in roughly ten minutes just before we start the shoot.
If you know of another photographer who can do all that, I'd love to have their contact info so we can chat. But as of now, it looks to me like I'm pretty unique in this specialized niche of the photography world.