I understand what the "show versus tell" part of your question asks, and your first paragraph has moments of showing rather than telling. You have a good start, but I'm only seeing a single paragraph, and it is very difficult to show a reader characterization within a single paragraph. Direct characterization can be handled easily within a single paragraph, because that involves you directly telling your reader information about characters. This initial paragraph does this by telling readers about Robert's drinking habits and how he loves to see his wife surprised.
Moving forward into additional paragraphs, you are going to need to have your characters carry more of the story. They need to interact with each other. They especially need to talk to each other, because that will help show your reader more of each character's personality. Dialogue will do this, because you can have a character respond "angrily," "patiently," etc. You can also narrate what a character is currently thinking. This kind of narrative information shows readers how a character is acting and responding, and that shows your reader information rather than telling your reader information.
If you are struggling with showing more information rather than telling, I have one more suggestion. My suggestion would be to change the narrative point of view from third person to first person. Third person is great, because the narrator knows a lot of information, but the third-person narrator tends to tell the story rather than being an integral part of the story. Try thinking about how your first paragraph would be different if you had to write it from Robert's perspective or Martha's point of view.