fulltimestudent "They entered into a relationship at a time when my friend was a youngish 60 and his new partner was a mature 28.They have had about 30 years together and have helped each other to prosper through those years. Now my friend is in his early 80s and his partner is close to 60."
Wouldn't your friend be 90 by now? Anyway, I'm curious how you came to know so much about this situation and are they asking you for your advice in terms of what they should do? Since it was mentioned, is it significant to the story that the two younger men are Chinese?
Either way, there are certain situations in life such as May/December marriages/partnerships that are rife with these kinds of problems and that's why they often are heavily advised against. Often the issues that inevitably arise in these relationships and in life in general, don't have a good solution or any solution at all. The only thing one can do is forget finding the perfect answer and choose a way to go that seems to be the least problematic and just muddle through the best one can.