Why do I think my coworker/ friend is jealous of me?

I was training a girl at work and she kept coming up and in other words interrupting me while I was training the new girl, and then trying to tell me I wasn’t training her right etc when I trained my friend / coworker myself and plus I have trained many people before her yet she tells me this to my face and this new girl wanted me to train her rest of the days so why and does it sound like she jealous of me?

Why do I think my coworker/ friend is jealous of me?
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