I don't mean to it just keeps happening!!!Well, why do you keep making Mjoll so upset!
I call him the "Ducky" of Skyrim. (Pretty in Pink, not NCIS. yeah, I'm old.)
...this Ducky.
I call him the "Ducky" of Skyrim. (Pretty in Pink, not NCIS. yeah, I'm old.) Kill him, have them follow you through the blackbriar Meadery, tell Mjoll to "Wait Here" then talk to Aerin, and go through the door to the Docks. He'll follow you to finish the thought where you can assassinate him without a witness, and dump him in the lake...
If she sees his body, Mjoll will mourn, and never come adventuring with you again. One of the reasons I actually prefer Uthgerd, she's a heck of a lot easier to get, and doesn't have all the Romantic issues. She also comes with a pretty nice place in the Cloud District (If you're not Crafting.)
If he bothers you so much, the solution is simple. If you married The Lioness, have her move into one of your houses outside of Riften.
Ask Mjoll to join you. This will dismiss Aerin from her service, and he will begin to walk home. All the way to Riften! Tell Mjoll to wait inside your home, she doesn't need to know about what happens next. Follow Aerin as he leaves the city and enters the wilds...The lonely, dangerous wilds. Why, if ever any harm were to befall him, no one would know.
That would be tragic. Wouldn't it.
It is rather selfish that you won't let her keep her pet. You don't hear Mjoll complaining when your Housecarl loafs about the estate all day, eating all the bread.
No wonder the poor woman's so upset all the time.