Well I know that the Cat is part of his dream, since the cat represent something-something that blocking him from getting close with flora, so what did Oscar actually do to her art? Also, how did the events actually happen? I don't believe the dream is super true since Oscar is written like a comical villain, and he is too much of a SIMP to flora to be that evil to her also he did like her painting it was shown in the gallery, so I doubt he destroyed it cold-hearted style.