Happy Ending for the Time-Limited Villainess is a Manga/Manhwa/Manhua in english language, Isekai series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

"Please have a happy marriage with me for just six months."
"What good does that have for me?"
“Of course we’ll give you the Reno family's estates and fortune.”"
“...Let’s say you give it all to me. You said you’ll divorce me in half a year. If that’s so, what will you do afterwards?”"
“...There’s something I’ve been thinking about doing. I won’t be able to use the money anyway.” "
Clea always lied. This body will soon die. It’ll barely last half a year."
After being in a satisfying marriage, Clea Reno wanted to close her eyes for the final time in a quiet place.