The Eternal Pause

Aiden Lark's biggest regret was his last thought before waking up in this new world.
He was supposed to finish university, get a cozy desk job, and maybe adopt a dog when he felt like being "adventurous." Instead, he died-he didn't know how or why-and found himself reincarnated into a world where people stopped aging at 18 until they met their soulmate.
Aiden didn't mind at first. He wasn't the romantic type, and staying 18 forever sounded fantastic. But there was one problem.
He reincarnated as the villain of a novel he had skimmed during a boring weekend.
The world was based on A Heart Untamed, a story he vaguely remembered as a frustrating romance-drama about soulmates and destiny. He'd reincarnated as Zayn Calthorpe, the scummy second son of a fallen noble family, whose only talent was making enemies.
In the novel, Zayn was a joke character. A petty antagonist who, in a desperate bid to age and restore his family's status, manipulated soulmate bonds. Naturally, he died a pitiful death at the hands of the protagonist.
Aiden had no intention of following Zayn's doomed path.
Rule #1: Don't get involved with the protagonist.
Rule #2: Don't provoke anyone stronger than you (read: everyone).
Rule #3: Find a way to age without the soulmate nonsense.
Simple, right? Well, that's what he thought.