My advice would be to let your characters dictate what they want to do. Or
not do as the case may be.
Don't forget, not having sex can still be helluva sexy. Think of all that tension building up...
I've written a couple of erotic UF romances, and when it comes to how often the characters have sex, where, when, who with...the circumstances pretty much dictated; an outline wouldn't have been able to force sex into the story where it didn't belong. (As it happens, both stories were pantsed.)
I have another project on the bubble that's not erotic romance/UF, but as you asked about mixing erotica with 'another genre', it still applies, right?
In this instance, I've thought, "Is this still erotic romance? Maybe erotica? Maybe it wants to be another genre, with a few steamy moments here and there."
What I'm going to do is just write it, and just as I play up the theme when I edit, I'll do likewise with the genre. Once I know what it is, I'll be able to tweak the manuscript accordingly.
That's probably very vague and no help at all, is it?