Too much cum, way too much
Yes she had cum in her mouth before, she also swallowed it before but it was very different the other times, not that she really loved it but it was ok, it was doable. But with cum you never know, where one shoots a few drops the other shoots a gallon, she is just unlucky she agreed to swallow from the cummachine. Even after he filled her mouth completely he keeps on ejaculating a couple of spurts.