Also, there is this one too:
http://www.mangago.zone/read-manga/i_m_the_prince_s_consort_candidate_however_i_believe_i_can_certainly_surpass_it/
I think you're looking for "Dareka Kono Joukyou wo Setsumei Shite Kudasai!" cause it sounds the same
Yes! That was the one! Thank you very much!
Although the ones you have menioned weren't what I was looking for, I'm thankful for your help
Hey, so I need help finding this manga I've read before. I'm pretty sure it was incomplete, but it was about this nobleman (I don't remember if he was a duke, prince, or whatever) that proposed a contract to the FL, who has a poor noble family and lives in a poor mansion with them, to be his fake wife so that he can live peacefully with his gf. The FL agreed only because she wanted her family to live comfortably. Anyways, overtime ML ends up falling in love with the FL and then leaves (?) the gf. If someone knows which manga I'm talking about then please drop the name of it