Call it The Sexorcist.
My Demon Lover, an unfunny comedy of eros, takes as its hero a schlep named Kaz (Family Ties' Scott Valentine) who literally becomes the devil when he gets sexually aroused. This presents many problems for Denny (Michelle Little), the peppy blonde for whom he falls.
Admittedly, Denny is something of an emotional doormat where stray dogs and men are concerned; even after her previous beau rips off the contents of her apartment, she still wants to work things out. Denny's fear is that, after the scaly, fanged Kaz has been leaving her bed so as not to hurt her, he has been hitting the streets as "the Manhattan mangler," a serial killer who preys on nubile women. Denny therefore must exorcise Kaz's demon, then hope that he is not the one responsible for the bloodbaths.