What should I do about an overprotective older guy cousin?

My cousin is 18 and I am 16 an he is really protective of me. he is like an older brother to me. He always tells me can't date and I shouldn't and that guys are no good. I want to date but I don't want him to be mad at me or scare the guy I'm dating.
What should I do about an overprotective older guy cousin?
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