Have an itch for something with... barriers. Some scenarios that have some kind of mental and/or physical complications for two lovers to over come.
A scaly partner that doesn't retain heat, stuck in the desert with a flame mage at night, or buried in an ice cavern, and while he has no clue about her predicament, she is too proud or doesn't like him.
A winged person with hallow bones, but fast healing, being helped along a treacherous mountain path by a paid guide, risking lethal injury at every step, but unable to fly.
A high school student, tiny and young, seduced by a far older woman, a teacher in her early 40's, though deceptively beautiful.
A father in his late thirties with a mysterious and somewhat eccentric daughter who begins to tempt him quite openly.
A student president approaching a younger and new student, openly interested in the boy, despite his assurances he is straight... though he can't help being a little interested.
Any other suggestions are welcome, as long as it contains some kind of difficulty, age difference, species difference, belief, region, magic, what ever.