The main character (MC) is a girl raised in a church by some nuns. I can't remember her name. She overhears the priest making a deal with a noble to sell her off as a "gift" for the local Duke that everybody has heard a lot of rumors about, like saying he's impotent/can't use his legs, etc. She asks her childhood friend to marry her, so the priest won't be able to sell her off after all.
Surprise, surprise, her childhood friend IS the Duke and he's been hiding his identity the whole time because of the rumors and he's been hopelessly in love with her since they were kids. He has abilities relating to the underworld - he can summon the soul of someone dead to interrogate them and his servants are all undead souls or demons called Reapers.
It turns out the main character is from the noble family blessed by some goddess? Except the family has been obsessed with keeping the bloodline pure; you know how that goes. So the goddess actually abandoned the rest of the family and once the MC awakens her powers, the goddess gets a material form and latches on like some overprotective helicopter mom? Meanwhile, the family found out she existed and still has the goddess' blessing, so the guy who wants to be emperor next, her cousin or something, wants to make her his wife to solidify his political standing or something.
It is driving me crazy that I pretty clearly remember the plot and lore but can't remember a single character name or the title. I only have the following apps for webcomics: Webtoon, Pocket Comics, Manta, Tapas and Tappytoon. I know FOR SURE it wasn't Manta or Tappytoon though.