It is possible to have a BDSM relationship without sexual contact. Note, I say sexual contact, not sex, as the definitions of sex given in this thread so far all seem to assume that 'sex' is a mental thing as well as physical. I have known of couples who have vanilla partners and BDSM partners and yet do not consider themselves 'polyamorous' becauase they do not have sex with thier BDSM partners. They go to their vanilla partners for sex and use their BDSM partners to satisfy the urgings for bondage and domination. There is often a lot of debate over this as to whether this constitutes polyamory/cheating and I don't think that issue will ever be easily satisfied.

One thing I have heard several long term members of the lifestyle say is that BDSM is not primarily about sex or sexual gratification. It is about the dominance and the control of an indivudual. Sex may be involved in that (it may even, as in many cases, be a primary method of control) but it doesn't need to be.

Of course, this is different to the relationship often lived by or aspired to by members of this forum that I have seen so far. By this I mean the 'BDSM marriage' (whether it is a real marriage or a long term relationship) wherein a Master/Mistress and slave live together 24/7 in an exclusive BDSM and sexual relationship. Basically, I think it just goes to show that there is a lot of variety in the lifestyle.