I mean, that's a very grey and complicated area. I had an ex who would do that type of thing, and it was never discussed but was absolutely welcome. I suppose after the first time you could argue some type of implicit consent. Or maybe I'm just a Stockholm Syndrome candidate.
I have no idea the dynamics of the Assange case, but the hyper-contractual notion of consent that has come into popularity in the last few years just seems to ignore the humanity of human relations.