Why did my ex stop staring at me?

Me and my ex had a messy break up 9 months ago

Since then he has had a girlfriend and whenever I would pass by him he would stare into my eyes without looking away and I would always catch him looking at me from a distance

all of a sudden he stopped doing that and would avoid making eye contact with me and going the same hallways as I go

why would he all of a sudden stare at me then stop if he says he didn’t want to talk to me anymore?

Why did my ex stop staring at me?
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