The supporting character's harem is very normal - Chapter 20: The curse

The servant looked at the grieving princess. “Your Highness, the Regent Prince sent your scholar fiancé to the Western Butcher’s daughter!” 

The princess gritted her teeth, speaking to her servant that it matters not as she has other suitors in line. Many days later, much to her dismay, the servant ran in a hurry. “Your Highness, the Regent Prince expressed his intention of becoming your suitor! All other men in line were sold to Gou Lan Red District!”

The princess was distressed. She said to her servant it matters not. She’ll soon be married to Prince Fuma. Then the uneventful came. The servant once more ran to her, almost tripping in the process. “Your Highness, Prince Fuma was imprisoned at home! Meanwhile, there’s a red sedan chair waiting at your residence for your marriage! It was led by the Regent Prince!

The princess was stunned. For a day such as this to come, it seemed impossible. This nothing but a sad story of a female boss crossing back in time to hold the thick thighs of the big boss. But while raising him, she was eaten in the process.

- Description from Novelupdates

18 and naive, Belle Hart thought marriage would end her misery, only to realize it had just begun!What started as a promising love turned out to be a facade, would Belle choose between a second chance or leave? She met her mate, the Duke, who she proposed to when she came of age.A month in, things took a turn. The Duke leaves for war before she could inform him about her pregnancy, only for him to return with a mysterious woman whom he claimed to be his new wife! The audacity! Trouble ensued and Belle suffered a miscarriage as a result.…“What did you just say?” He asked, his gaze darkening.“You heard me well, I seek a divorce. I wish for us to go our separate ways,” she replied, her voice steady as she met his gaze with confidence, though inwardly she was shaken by his presence.“You are my mate, Belle, and I am yours. Divorce is the most foolish notion you could entertain. Do you believe any man would take a worthless creature like you as his wife?” He scoffed, his words biting, causing her heart to ache.…The Duke's refusal pushed Belle into the arms of the king. All she had to do was bear him an heir and he would help her get her revenge!“I want you to marry me, Your Majesty, and aid me in seeking my revenge against the Duke and those who have wronged me. In exchange, I shall bear you an heir before you help me,” she said, her voice steady and full of purpose.What will the choice be?

Jason, a young man who died after getting involved in a brutal accident that killed him reincarnated into the exact novel he was reading on the night he died.He was reincarnated into the novel he was reading before his untimely death, as a baby who had just been birthed successfully. From his birth he was shown no love due to his non-existent aptitude in magic.Lucky for him, he awakened the Talent system.A system that allowed him to copy talents; skills that individuals excelled at, the skills that made said individuals the cream of the crop. With the exact same mastery of the person he copied it from.The system when trying to increase his aptitude for mana only managed to decrease it even lower blessed him with nature energy to passively strengthen himself.With no magic and a system that allows him to copy talents, watch Jason climb through the ranks of the world and become the strongest!...[Host can choose a talent to copy: Null eyes, War God's Embrace, 30 Blade movements, Advanced War Tactics]

I was thrown into a novel that hasn’t even been completed yet (and turned into a girl…), guided by the omnipresent voice of the unreasonable, amateur Author as he writes the web novel. I have no idea what’s going on, so I have to stick close to the main character to make sure I don’t hit a bad end…Why are you treating only me like this!I’m not suspicious, believe me.I’m a harmless person.“A villain? Not at all.”