Why my ex is always bragging?

My ex boyfriend is always rubbing things in my face like that work is good and he's making lots of money or that he is doing lots of trip and partying a lot. We don't talk much and I just try and be friendly and be a nice person back even though it really gets under my skin and I do get jealous about these things. And he doesn't ever seem happy if something exciting is happening with me. I work hard to be able to do fun things with my friends and It makes me feel like my life isn't as cool or something as it should be. It seems like he is having an amazing time, and most likely seeing lots of other girls. I know its immature but like why does he feel the need to always boast about what is going on in his life? and rub things in my face?
Why my ex is always bragging?
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