How can I stop being obsessed?

Me and my homie where talking about this girl we’re friends with that I recently stopped talking to because I have feelings for her and he mentioned another guy that used to be obsessed with her and got blocked. All of a sudden I lost my appetite and felt really weird. Why does it bother me when other guys like a girl I like? I know I’m a bit more preoccupied with her than I should, how do I stop?

P. S. Not talking to her is helping to get over it but I’m curious why I feel like this
How can I stop being obsessed?
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