The lesson on Rose Marie (1936) states that Nelson Eddy commingles with MacDonald vocally. I find this very interesting especially during the Production Code, because the commingling is not directly explicit but implied in different ways, here it's through singing and through the glances the characters give to one another. This is one creative way that production code films abide by the rules while at the same time subtly breaking them.
The first scene shows a romantic scene, with the lieutenant serenading Jeanette Macdonald’s character on the boat in the river, under the moonlight. And yet, the two characters still refrain themselves from even making eye contact for too long. Macdonald looks back at him a few times, only to quickly look away.
The second scene shows that the bar is a place where sinful acts occur, such as drinking, couples outright courting, dancing, and touching, and gambling. Jeanette Macdonald functions as the moral, well-behaved lady who is obviously out of place in the bar. This is evident through her classical singing not suitable for a bar, and her mannerisms and visible lack of comfort in the environment. I suppose it's thus suitable that she is the leading lady and in the end gets love and the handsome man. The other lady in the bar takes over and begins to sing differently, including dancing along and moving her hips to and fro. Jeanette Macdonald imitates her movements but it is evident she is not “truly” like the other woman. The men cheer for the second woman after she finishes singing. And, again, the woman at the bar who swings her hips does not win the lieutenant, which goes back to who is “worthy” of getting the leading man and finding love.