My bf and I had this very same discussion last weekend. After almost 2 years our relationship is real and meaningful (not just for the 2 of us, but for our whole quad) but we have no choice but to keep it a secret. Even a rumor of it could lose him his career.
We have many of the same friends and spend lots of time around each others families. We're often out in public together and because we are two married couples, people just assume we are best friends (which we are) and nothing more (nothing could be further from the truth). But keeping this secret which is in reality an amazing, beautiful, meaningful relationship really does feel crappy. It cheapens it somehow and leaves me almost sad after spending time together around other people.
After our talk, for the rest of the weekend, my bf went out of his way to acknowledge me in little ways even when other friends were around. And to find ways to let me know he was thinking of me even if he couldn't touch me without raising suspicion. It helped some and was sweet of him to do that. Still, what we have is incredible and I wish we could let others know about it. Maybe someday we could at least tell select family. We'll see.
I wish I had the answer for you. I don't. But I just wanted to tell you that you aren't alone.