Bah, take him to the sex store, pick out some straps, and go at it. He isnt going to "not" like it trust me. I'v been with my girlfriend for about a month, and for some reason I think we're more open then people that have been together for years. You just have to be 100% open with things when it comes to what you want in bed. I mean we are idiots when it comes to sex, but if you tell us what you want, where you want it, how hard you want it, etc.. we wont complain. Just simply tell him you want to be tied up, and take it from there. good luck!