I hate to say it, but I need to play devil's advocate. I just wonder if your friend is hiding the truth from you. IF their relationship was loving and healthy as he claims, then there would be no reason why she would abandon her own family, unless he had hurt her somehow. Perhaps he was abusive or severely toxic? How much do you really know of your friend? Abusers will hide their abuse from their friends and will lie to their friends. It just doesn't make any sense unless something drastic happened between them that is not telling you about. Something to think about at least.