The story is not about Usagi becoming a wife.
So a good compromise/end for me would be:
1. wedding with mamoru + friends
2. talk with luna
3. monologue
The End
Having a wedding dosen't mean the manga goal or was to become a wife .Your also forgetting Mamorou, and Usagi relationship was one of the huge aspects of the manga.Ending it with a wedding a party with all the senshie made sense.In Crystal Tokyo.
You keep forgetting that she is a queen now.That she is ruling with Mamorou, and soon will have chibiusa?
You really think it's sexist? That it's sexist to show at the end.To show she is happy.She is getting married to the man she love.A man she was not allowed to be with in her first life.She with her friends as support .Going through all the trauma, and death.Also none this means she is going to live happily ever after.Parts of Chaos is still out there.She is still a Queen, and have work to do