Part of "withholding" is that not every thought you have in every instant is instant intellectual property of your partner just because you are in a relationship, open or otherwise. I know I had Nyx over at my place the other day and as she left had a conversation something like:
N:"hmmm... I just thought of something."
N:"I'm just going to wait and see, I don't need to say it yet."
I asked her about it a few days later and she didn't even remember what she was thinking. This might bother some people but I'm okay with it. Whatever. We have something like 8 million thoughts/feelings/memories a day bouncing around in our domes. "Tact" is about knowing what to say and when to say it. Complete honesty is a good ideal but should be tempered with a little wisdom and tact.
Often he had been often bound with fetters and chains, and the chains had been rent asunder by him, and the fetters broken in pieces: neither could any man tame him...and he asked him, What is thy name? And he answered, saying, My name is Legion: for we are many.