Ookami-heika no Hanayome

Mr. childhood friend gangster is going to try to kidnap the king, out of jealousy plus thinking he's a bad man who will take advantage of Yuurin if not stopped. That should be fun one way or another.

I kind of get the feeling they are going to try marrying her to someone in the next chapters

He falls for her pretty much instantly, but she's scared of the ruthless, harsh king figure. So he explains to her that really, he's a quiet unassuming guy who just puts that on to survive the tough world of being a king with all these nobles jockeying for power and so on.
This is not, basically, true. He's actually putting on a quieter persona to get closer to her.
Meanwhile, he doesn't want to let her know he's in love with her until he's pretty sure she likes him back, while she doesn't want to fall for him because she knows she's unsuitable and basically just a place-holder, and wants to concentrate on getting this gig over with, with enough money under her belt to take care of her family. She has fallen for him, but is holding back because she figures that's a recipe for disaster.