In many paranormal erotic romances I've read, there is often frequent, non-monogamous sex, especially early in the book and often in the first scene. Sometimes even gratuitous sex. Complementary body parts flying around, diving into whatever orifice is readily available, because that's what shifters or vamps or demons "need".
Don't get me wrong. I love to read and write paranormals. I always get a kick out of this truism of the genre though, not only because it's sometimes fun to read a down and dirty scene without a bunch of emotional baggage, but also because it's a somewhat obvious trope. They aren't human. Therefore, sex is just that...sex.
Paranormals aren't the only place you see this play out. You could also insert other genres here, including macho men occupations such as military, or ex-military special forces types (lots of those running around apparently), cops, etc, where the 'humanity' has been stripped from the heros, the better to do their jobs, which usually involves the need to kill without qualm.
However, don't forget this is a romance. So sure, there will come a time in the story when love begins to rear its ugly head, and won't THAT be a fight for all involved. The protagonist will be disparaged by another non-human entity (or fellow macho man...or their own subconscious...or sometimes even the object of their affection), will be sneered at for being too human. Love is seen as a weakness, a failing, a vulnerability to exploit.
Ah, but love will triumph. And while the no-strings rampant sex always reads like it's on fire, there is no comparison to the incendiary sex immediately following the realization (and before the end of the story, the declaration) of love. The tenderness, the emotion, the connection between the participants is unprecedented, unparalleled, unrivaled. A satisfying completion for all involved, including the all-too-human reader...
Some thoughts from people who say it much better than I ever could. Vote for your favorite; the winning quote will be used in my future book, Sex On Summer Sabbatical.
"Sex without love is as hollow and ridiculous as love without sex."
— Hunter S. Thompson
"Sex is the consolation you have when you can't have love."
— Gabriel García Márquez
"We can live without sex, but we can't live without love."
— Shane Claiborne
"If Jack's in love, he's no judge of Jill's beauty."
— Benjamin Franklin
"There is a no man's land between sex and love, and it alters in the night."
— Norman Mailer
"Well, in that hit you miss. She'll not be hit
With Cupid's arrow. She hath Dian's wit,
And, in strong proff of chastity well armed,
From Love's weak childish bow she lives uncharmed.
She will not stay the siege of loving terms,
Nor bide th' encounter of assailing eyes,
Nor ope her lap to saint-seducing gold.
O, she is rich in beauty; only poor
That, when she dies, with dies her store."
Act 1,Scene 1, lines 180-197
— William Shakespeare (Romeo and Juliet)