Thanks for the chapter!
If Mio is being affected by the curse, why hasn't the mark on her neck appeared?  Personally I think half of Maria's story about the elixir is bs.  Since it's a succubus recipe it's likely to be half aphrodisiac absorbed through the skin.  As for healing wounds and curing fatigue is true as a means to extend how long can have sex as rough sex can cause injuries, like scratches from nails, while curing fatigue would allow the participants to go a few more rounds rather than passing out from all the exertion.