Lmao. Either you are an imbecile xenophobe or just playing dumb if you think the typical sinkies ah lians and ah bengs in ours school are incapable of this kind of silly behaviour.
It has nothing to do with capable or incapable of doing, but just not the Spore culture to splash paint for stealing boyfriend, you mean prior to this you have heard before of students doing so? Splashing paint and doing it so publicly in canteen shows this person is lawless, nothing wrong to guess very likely to be foreigner from lawless country or some other culture where it is the norm to splash acid after being spurned or rival or enemy, so splashing paint is nothing to them.
teenage girls at this age are very vulnerable, last time, i know a group of convent girls who will mass slash their own wrists and drink dettol either over boys or some insignificant stuff. not joking, whenever i recall these incidents, i never fail to laugh at their stupidity.