Sometimes i don't really understand the logic of not wanting to add more Harem members given in the plot.
I mean, it wasn't MC who fell in love with Meirias and chose her as his 2nd partner.
Meirias fell in love with him, and it was Ricolette who proposed Meirias to marry MC along with her.
And now she is blaming MC on possibly falling in love and marrying another girl?
I mean, technically MC didn't really fall in love with either of them.
His marriage with Ricolette was by a Royal Order which she accepted even-though MC gave her the option of opting out, while he married Meirias to respect and accept her feelings.
So, why blame MC for falling in love with a possible Female Slave in the future and having her as another Concubine?
Not to forget, in the Manga, MC didn't even spend proper married-life nights with either of them (in the Novel it's clearly mentioned that he sleeps with both of them on a regular basis, but that did not occur in the Manga yet especially with Meirias).