We live with her to caregive. She has Dementia and thinks he is her man. It was cute at first but now she is getting very angry and jealous with me- like she is in high school competing for his attention. Its very stressful for both my fiance and I when she gets angry over it. I dont want to correct her but Im running out of ideas to distract her. She has always had an eye out for a man! But I never thought it would be for MY MAN.. haha
IMHO, if the dementia is that far, you probably will never get her to stop. She just is not capable of processing reality any more. While not deliberate or malicious in intent, this is still not good and could, and probably will, get worse. And it very possibly will impact your relationship with your fiancé at some point. It may be time for you to start exploring other options for her.