I can fully understand why JWs are guilt-ridden over sex. The WTS intrudes on every part of the lives of members, telling them how to do everything except how to wipe their butts. Stern directives have been made about what is and is not appropriate in the bedroom between married couples, which can only inhibit young couples in discovering their sexuality and make obedient Witnesses feel guilty about even wanting to do certain things.
The pressure to inform the elders of any behavioral aberration would also stop many partners from even voicing to their spouse a preference for any particular sexual activity lest their partner decide to "seek assistance," thus guaranteeing half the congo would know inside a week.
I recall some years ago a prim elder's wife commenting on a TV program she'd been watching which showed some sexual activity .... "The woman was on top, I mean, it was almost pornographic!"
And it all starts so young, with frequent admonitions in books, magazines and public talks (for God's sake!) about the "problem" of masturbation, telling poor young buggers to confess to the elders and, again, seek their help. The more they focus on it, the guiltier they feel and the more screwed up they get.