Congratulations!
If I was to enter a serious D/s real time relationship, it would be one where I'd be thinking about marriage down the road. After all, if you can share a bond that requires as much trust and respect as D/s, and if you're truly into each other for more than sex, it shouldn't be that big a jump to husband/wife, would it? The founding principle of a good relationship of either form is trust, after all.