When I want to have sex with my wife I dont get an erection until I FANTASIZE that she is having a threesome with another guy along with me. or she is having a gang bang with number of well hung men.I SOME TIMES pursuade my wife to watch porn with men showing their long erect dicks. but my wife does not like to see them. Is something wrong with me? How do I stop this behavior and have normal and good sex with my wife?