Power imbalances and adult victims
There’s a very incisive article at New Matilda about the power imbalance in the NRL/Matthew Johns/”Clare” episode (Disclaimer: In that case, Clare is a pseudonym, and I am not 19 years old 
) and how that power imbalance affects the issue of “Clare”‘s consent. However, I think there are a couple of points that the writers fail to make.
Firstly, that when consent is apparently given in an environment of coercion and/or power imbalance, it is, by definition, only after the event that the victim can really say whether she consented or not. And understanding that is crucial to appreciating why “Clare” did not object at the time, but only afterwards. In other words, only complaining afterwards is not necessarily an indication of a changed mind, but of a victim freed from the power imbalance or coercion and understanding properly just how that power imbalance prevented an informed consent at the time.
The other point that I feel the writers do not adequately explore is the label “group sex”. They rightly point out that “group sex” is a bad term for what happened, but fail to say why, or what would have been a more accurate description. Extrapolating from the rest of the article, I think that their perspective would be that “group sex” implies a degree of mutuality that is contradicted by the circumstances being the presence of several high-profile men and one young woman. A more accurately descriptive term might be “pack sex”.
According to Matthew Johns’ account, after it was over, he went to “Clare” and apologised about the others coming into the room. (According to quotes from Johns, initially “Clare” went to the room after an agreement to have sex with him and one other player, and he was unaware when others entered the room, and stepped away from the bed when he became aware of them.) However, that fact alone makes it very clear that “Clare” had NOT consented to their presence beforehand. But since “Clare” says there were six male participants and another half-dozen or so spectators, (and this number has not been denied by the police, who investigated the allegation at the time, or the club, who must also know the names of those involved), and given the public behaviour of footy players in the context of their sport (an emphasis on group activity, spurring each other on, on-field brawling, and egos fed by cheering), it seems very likely that whatever “Clare” consented to initially became something completely different when an extra 10 or so men entered the room. In such a situation (and particularly if the young woman had previously suffered some abuse), it is extremely unlikely that she would have been able to call a halt at the point where she felt that things had gone further than she wanted.
I think it highly likely that it was the cheering (each other) of the first few men that drew the others’ attention to what was happening in the room and caused them to enter and so “join in the fun”. And I also think it likely that if “Clare” had objected at some point, the guys would simply have ignored her, or possibly even have prevented her from leaving.