Some paraphilias are similar to behaviours most of us do not find unusual or disruptive to satisfying interpersonal relationships and are perfectly normal such as a husband's greater arousal when his wife wears black, lacy underwear. This kind of behaviour only becomes a problem (and is then called a paraphilia) if it involves the NECESSITY of a particular object or behaviour for the person to achieve arousal and satisfaction, thus interfering with the development or maintenance of an intimate relationship between two whole, responsive, loving individuals.
Other paraphilias involve more dramatic behaviors that most people find more incomprehensible and about which sexual partners are likely to object (such as a husband not being able to become aroused or have intercourse UNLESS his wife ties him up and treats him like a slave). The most extreme of these behaviors include some that are truly physically and psychologically harmful to others, such as rape and lust murder. Paraphilias refer to behaviors, NOT fantasy. IMAGINING unusual sexual situations or behaviors to enhance stimulation or arousal is not uncommon."
Reinisch, June M./Beasley, Ruth: The Kinsey Institute New Report On Sex, What You Must Know To Be Sexually Literate, St Martin's Press, New York 1990, p. 157-158.