Married to korean for 30 years

hello everyone, been married to a korean woman for 30 years. we live in southern california (25) years. weve raised 2 wonderful kids, all grown up now. we've been on our own with no family around for the entire 30 years, just each other to depend on. thats not an easy path to go down but because of the love we have shared we made it work, until 5 years ago! I've been watching my wife self destruct the last 5 years, I know theres age issues (metapause, midlife crisis) absolutely nothing i say or do has made any difference. no matter how much i show her that i care and love her she cant see it. It seems as though only her culture she can feel now. weve been so isolated in our experience that ive never even talked to someone whos been married to a korean woman, thats why im here at this website. im hoping someone will read this that has been married to a korean woman for a long time. is this common for a 50 year old korean women  whos been married for 30 years to an american man  to completely reject anything other than korean culture all of a sudden at midlife?   our marriage is disintegrating before my eyes and i feel totaly helpless.