About six months ago, I wrote a post called I want to tie you, not marry you... (intimacy in the scene) about how a scene can be intimate without implying more commitment beyond the parameters of the scene itself. But that's only half the story....
It can be really confusing when you're new to the scene, to see such incredibly intimate acts being done in front of you. Maybe they're things you've done only in the privacy of your bedroom, or maybe they're things you've only dreamed about in the dark recesses of your mind- and here they are, being played out right in front of you. Additionally, BDSM culture is intertwined with polyamarous culture and it can become very confusing to know where the lines of intimacy are drawn.
But the truth is that there are lines for many people that we don't cross.
For me personally, intercourse is one of those lines. If it involves my penis entering into someone, that's no longer strictly play. That line of sex is a common one, but not the only one.
I know people who won't use certain toys with people outside of one person, who won't take on certain roles in a scene except with one person, who won't use certain special phrases such as "Good girl" except with one person, or who won't do certain kinds of intimate activities (such as hypnosis) except with one special person in their lives.
My previous post encouraged people to allow themselves to explore themselves through play and to expand their ideas of intimacy through exploration, and I still believe in and encourage that- but exploring yourself does not need to mean that you don't have personal boundaries or special things that you only share with one specific person.
Remember that the beauty of the BDSM community is the ability to explore your inner world with others, that doesn't mean you have to let go of having special, sacred things with someone you love.