They are pretty good friends of mine and I never sensed any tension. It really was a marriage-ending bolt out of the blue, like discovering an affair or severe financial infidelity.
Everyone noticed - and of course I've seen it from the other side, too, many times. You can't hide when people are together who don't want to be. That always shows.
[1] https://gwern.net/doc/psychology/personality/psychopathy/194... - despite the filename, this is the 1988 edition. I like my paper edition (I made my paper edition) but the PDF will serve well enough for your reference here.
Try not to develop AI psychosis before it does. I have had the regrettable privilege of seeing that close at hand quite recently, and it looks like something that can get to be extremely difficult to come back from. Like digging a hole so deep, you end up pulling it in after you.