Sometimes it happens.
An emperor takes in a concubine sometimes not because he wants her but for other reasons.
Like politics, her family a high Nobel family maybe gave her as a gift to the Emperor.
And he didnt refuse so not to alienate them.
Or he took her in as a condition from her family. If he wanted their land, resources, money, power, or something and they would support him if he made their daughter his concubine.
That's my guess.
That's why maybe she never met him since held no real interest in her and never met and spent a night with her. He just ignored her and let her do whatever she wanted that was limited.
She's a concubine in name only
Wow thanks for the information!!Σ>―(〃°ω°〃)♡→
Even though she is a concubine, has she never saw her husband's face?