Because he’s a Padisha. His honor is on the line if one of his concubines sleep around. It’s like shitting all over the emperor’s authority and honor. Like mocking him.
Plus, why bothered him too was that the male concubine talks about love, but has no problem sleeping with someone else. Throwing the word “love” around so loosely when he’s been trying to get closer and waiting for Tei for so many years it’s like the concubine is laughing to his face.
Also, I forgot to mention that, anyone saying they love him, could cause feelings of distress in Tei. And he doesn’t want to make Tei feel uncomfortable in any way. That’s why he forbid any of his concubines to love him. Only Tei is allowed to say he loves him. That’s why he was so angry, bc the male concubine talking about love, would marry Tei feel insecure.

Can someone explain to me why he's mad that Rhyvann (the concubine) was sleeping with another man? I'm guessing Shuraka visited the concubine the night before to observe how to pleasure Tei. If he has no feelings for the concubine, then why does he care if Rhyvann is trying to gain his attention?
Is it because it's disrespectful for the concubine to sleep with a man without the Padishah's permission?