To add, depending on the context, this could also be a sign of controlling behavior. Policing who your partner is friends with is pretty classic controlling behavior, but insisting your partner not be friends with their preferred gender is also "normal" in certain circles. I don't think that's a healthy norm, but it is important context.

For instance, if someone's partner said they couldn't be friends with men/women, and then tried to create distance between them and their family, then I would advise them to leave that relationship immediately. That would be a dangerous situation.