Contract Marriage

So, this is technically cheating. There is a contract engagement, but it's so obvious that it's a sham from the start... still putting it here :)

There's a contract engagement that comes into play around chapter 30ish, but it isn't really the focus. Sold as a GL, but the end game is Het. It's frustrating.

Yes, this counts! Akane and Ranma's marriage is ARRANGED by their fathers!

Ciel is in an arranged engagement with the ML due to a REALLY complicated reason, but yeah it's a contract so it fits.

MC (FL) goes to find a finace after the man she thought was interested in her gets engaged to her "sister". She ends up making a deal with the captain of the holy knights. This is all so she can inherit her RIGHTFUL place as the family head.

Litheria, now on her third life, proposes a contract marriage to the Grand Duke, Pellus in order to completely avoid the plot of the novel she's been reincarnated into. This is solid romantic gold. All the "drama" is from outside of their relationship. They are perfect for each other and truly make the other shine. I love it!!

Contract engagement, not a marriage, but I'm putting it here.
Our FML wakes up after being sentenced to death via poison and finds herself inside a book, where the characters all have the same face and names as people from her original world. She recruits the villain of the book to help her deal with some family issues, and to help him not become "evil".