Wow, JCJ that's a tough spot to be in. In one way it's their business but in another it's yours too because you love them both. Tough convo to have especially in a family that talks about nothing! Voldemort (my stbx/wife/whatever) had to deal with this with her father. He'd been having a A for 20 years and he mom decided on a trip to Canada that she would reveal the whole thing to the family. Voldemort had to go to a family meeting to discuss Dad's infidelity. I was stunned. I said "but isn't this kind of their business?" She replied "we are a Chinese family, it'a all our business" At least there she had back up with sisters and brothers but...wish I had advice. Is there a way to open discussion through the back door somehow? Maybe say "Dad, I've been having some thoughts and feelings about you and Mom, is everything OK? Is there anything I can do to help?" It might not get much but it tells him that you are noticing. Only advice I've got for now.