The problem is that Mike is too dense to understand when things are happening to him:
because he suffers from the delusion that he's a keen-eyed observer of human nature when he's really just a muppet lost in the ozone.
There is also precedent for Gordon serving as a go-between when Martha wants to make things up with Mike when they go too far. This will happen this August when Jason acts like a normal teenager and moves onto the forever-and-always love of late summer:
The problem is that Mike has to see a real person with wants, hopes, needs and dreams:
and he just can't do that:
You might as well ask him to listen to conversations that aren't one hundred percent about him and his own feelings:
What this means is that he's the only person on Earth who doesn't realize that people see him as having dumped Martha in the most cold-blooded manner possible. It also means that explaining this to him would be an exercise in futility because it requires him to do something he cannot: put himself in the place of another person.