Seriously... I got really sad when I hit 10k and realized this. I thought there might be a special "Yay 10k affection!" ending conversation, but there wasn't and I was severely disappointed. Especially after getting married and all, I assume they would at least say different things. It could also be nice to have an optional title, like with their last name added onto yours or something xD Although that's probably wishful thinking. Haha.
This is something that I had wished for as well...it would add an extra level of depth and emotion to the story that I think it's lacking a bit. Not to complain though, I think the companions are done really well, there's just so much untapped potential that they hopefully take advantage of in the future.
Sigh...here's hoping.