Louisa, both before the wedding that wasn't and at her baby shower, was in that peculiar position of defending Martin from the criticisms of the townsfolk, even if they were the very thoughts she had herself.
He might be a "gruff, monosyllabic, rude" tosser, but he was HER "gruff etc." tosser and nobody better say anything bad about him
I remember once many years ago a British tabloid trashed Michael Jackson (okay, yes, I know). David Letterman, in a monologue immediately after, basically said, "How dare they?" Michael was, he said, a "space cadet", but he's our
space cadet, so they need to lay off.
I completely agree with your statement that he was her
gruff, monosyllabic, rude tosser, so she always defended him. This scene, to me, was another obvious sign that these two were still a couple, throughout S4, just having an extended row. When I first watched the baby shower scene, I felt relieved. I knew they'd end up together.