list it in your preferences, polite pm if someone misses it. i wouldn't be offended unless you made it weird. if someone's mad at you, then no harm, no foul in leaving them hanging.

as you can see, a bunch of people are projecting hardcore onto your relationship with your friend already, so i'd keep it to the point if it does come up without giving too many details. give people less of a reason to headcanon some fuckwild shit about you and your friend, you know?