In the subject-object mode of sexuality (or subject-subject, it means the same since the “other” is treated as objectively present, whether they’re referred to as another subject or not), there’s a masculine and feminine way of experiencing sex, which are very different from each other. The masculine means of “objectifying” the other and subjectivizing themselves – experiencing sex from the perspective of the “I”, not the Self, is really masturbation with someone else there as a prop. The feminine means is to experience it as a narrative. Perhaps it sounds harsh to say that the common feminine experience of sex relationally is primarily as something to be discussed afterwards, but even though they may enjoy the sex at the time as well, that enjoyment itself contains an element of narrative distance, as if they are already observing the act and turning it into a story. Some men of course experience things in the feminine manner and vice versa. You’ll notice that ‘feminine’ types who experience sex in that way are the ones who take up the most space (almost all of it) online whether on BDSM or on vanilla relationship sites.
Beginning with a fantasy explicitly though can result in a different reality. The a priori fantasy removes the “I-subject” as the focus of the experience, hence there is often tendency to talk in third person because somehow saying “I” feels odd, while saying “me” doesn’t, but where “me” doesn’t grammatically fit using third person is the only available option. But this provides the possibility for each to experience sex topologically, not relationally, from the places they occupy in the fantasy, and the resulting real situation, the resulting shared Self, arises out of being in those places. The is also a more intense experience, because it’s not an experience of doing something with or to an “other” that is irreconcilably distant, but an experience of a shared being-together enacting the very means by which that sharing arises.
If the RPG player is more themselves in their fantasy character than in the person they play in “real life”, the BDSM play scene takes that one step further, in that roles are still being played, but they’re being played in a more realistic physical manner. However the people playing are still not willing to accept that that persona IS closer to their real Self and actually enact the role as much as possible in their “real life”. Hence the insistence with many people that “they’re always dominant except when playing” or the need for many tops to appear super-sensitive to the bottom when not actually playing. The discomfort of people into BDSM from a play perspective with those who enact the role to any degree in real life, which in my experience is much more intense than the discomfort for vanilla people, comes out of this combination of a desire to enact it more fully with a lack of confidence to actually do so.