It’s per booking, and they divide the price between the two parties. For me I found all the extra stuff wasn’t worth it and next time would just opt for a couples Swedish massage instead and save the $$$
You get a milky foot bath, 20ish minutes hot tub time on a private balcony, a 75 minute massage, and then time to lounge on a big lounger while they serve you tea and fruit. My experience was on the Fantasy.