This, my fellow Flutherites, is an interesting question.
My first guess (and perhaps hope for you) is that this is an offer of very psychological lovemaking.
This doesn’t fall under BDSM necessarily, but it would be mental DS (dominance and submission).
Since this has happened twice with as many partners makes me wonder if there is something about you that hints to these women that you are a natural submissive that could enjoy some humiliation and psychological dominance.
This can be white searing hot if you have a little courage to ask meekly yet confidently “but why?”
Over the years I have taken the BDSM/DS world tour, almost always as a poised and self confident submissive but one lover’s utterances stuck with me well:
A curvy and intriguing PR consulting firm owner Jewess would repeat during vanilla sex “don’t”, “no, stop.” It was all I could do to keep these utterances from sending me over the edge far too soon.
Had I felt like the relationship was going to last for some significant time I would have responded during the act and asked where the whole thing came from afterward.
I think you have a chance for something special here.