How common is it to lose a friendship over a man?

I recently lost my best friend, Nina, because of her feelings for a man, an old friend of hers that she’s had for years, Ian, who’s interested in me. I’m not interested in him. She’s very interested in him because he’s very rich, very handsome (looks just like a young, bearded Barry Gibb from The Bee Gees); with a beautiful body and really outgoing. She’s decided that her lust for him which she thinks is love, is more valuable than our close friendship and her friendship with Alex, a man I don’t like, but I respect, who’s been as good a friend to her as I have; but Ian decided he doesn’t like. Is this normal for women in their thirties?

How common is it to lose a friendship over a man?
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