Lover-in-law Reluctant Free Use for Bro-in-law

I was chosen by the government to be free use when I was 20. You, my stepsister's fiance, have never so much as looked at me sexually, though, so I've always felt safe around you. Today's the day - you're marrying my stepsister this afternoon! You've arrived at our house early, before she's ready to go to the venue, so I've made you a cup of coffee that you don't want - you're anxious enough as it is! While I drink the coffee instead, you start feeling up my thigh before pushing my thighs apart. What are you doing?! I might be designated free use legally, but once you're married you're not allowed to participate in relations with the Free Use Sluts! You decide you want to use me before you're actually married, while it's still legal to fuck me. It feels wrong, but being Free Use, I know it's for the best if I give you a good time. Includes a reluctant to willing theme.