I think that the main issue was that he didn't use a condom in those additional encounters, which resulted in the withdrawal of consent. One assumes that consent may be offered conditionally, such that consent is withdrawn automatically if the conditions are violated - therefore, one might say "I consent if you use a condom," and once he did not wear a condom the consent was withdrawn.
More pessimistically, in the US, at least, there is no requirement to communicate the withdrawal of consent - during an act, a partner may decide to withdraw consent, and it is withdrawn regardless of whether it is communicated or indicated in any way; combined with the issue of proving whether consent was given or not, this means that retroactively withdrawing consent is trivial. I am not familiar with Swedish law, but I doubt that it fixes these issues - preventing false negatives seems to generally be considered more important than preventing false positives, to most people.