Do you need one for a successful D/s relationship?

I mean...I understand the point of "play-partners" or playing with someone at a club one time. No emotions involved (or at least just not anything extraordinarily deep) and each of you go your separate ways afterwards...no emails, no phone calls, no secret meetings in the park. And really, for someone who is married, this may sound like the ideal way to go. But is it?

We all talk about trust....and how trust is built over time and that trust is essential for a healthy BDSM D/s relationship. But with trust and "time" come emotions and feelings. What do you do when you find yourself starting to care what your D or s ate for breakfast or whether he or she thinks about you as much as you think about them? Now, what if your D is poly? And he or she has 1 or 2 (or more) others?

Will there always be a nagging need to keep a wall up between the two of you? And whose responsibility is it to maintain that wall...that separation? I presume it should be the responsibility of both parties involved...but then *really* letting go and allowing yourself to embrace your D/s role may be difficult.

Any feedback is much appreciated. Thanks!