When men talk about platonic relationships they almost always don’t mean what they are saying. When women talk about them, they are being naive.
Regardless ??? ?????? ????? ???
There is no heter in halacha for such relationships with women.
When it comes to a first cousin, (especially if the families are close) I don’t think you have to treat him or her as a total stranger. However there can be attraction (cousins marry sometimes) and you should use common sense and not become “friends”.
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