A Bit of a Cliche, but Something I Love (M looking for F)

[tdee8008]

 Hello.  I've been browsing, and I'm really impressed by the imagination of the people here.  My own RP ideas are fairly straightforward in comparison.  Still, I like them, and I want to describe one of my favorites. Maybe someone here will be interested.

Basically, it's the story of a newlywed man (me) and his wife's younger (18-20, give or take) sister (you), and how one of us seduces the other.  Either I'm completely in love with and devoted to my new wife,  and you're a seductive vixen determined to get me to cheat, or you're a fairly quiet and innocent young woman, and I'm bawdy, worldly, and out to bed you.  Either one works, as long as one of us resists for a while,  before finally giving in.

Alternate idea:  same as above,  but you're my mother-in-law rather than sister-in-law.

I'm open to creative suggestions for improving the story, as well.

Thanks.