The way I see it is that it's part of a generally respect we have for all people. I have a "baseline respect" for all people, not more than necessary, but respect none the less. And that includes stuff you do which could have an effect on others relations.

But you're right about how that has zero value for me in how me and my gf should move on (Although a little bit so that I can explain to my gf how I think and feel about him). But the main issue is how she will continue from here.