That is so sad. I used to have a male friend who loves his ex gf so much that even he had a gf at that time, he kept thinking about his ex. (his ex got married with someone else)
Then one day, out of the blue, his ex gf got disvorced and my friend was so happy, he dumped his gf the first thing, then went after his ex gf.
But his ex gf would not go back to him even after. I think this is so dangerous and so sad.
Your female friend must be upset and could feel so insecured about this. Not too fair to her as his husband is her most loved person.