Contract Marriage with a Yandere

Marcus woke up to find himself transmigrated into the dark novel The Nightshade Tragedy, becoming that very same street-roaming scoundrel—Marcus—who deceives and marries the disabled heiress only to end up as fish feed in the end. Faced with the female lead, Elena Nightshade, who appears sickly and coughs up blood on the surface but is actually ruthless and merciless — Description from novelcodex.org