These guys are just fodder of useless(Mr. Kielhan and little Prince Oscar) or trashy(Mr. West Emperor I'm looking at you, you landfill of trash) men to bring up the MC's value as a woman and Crown Prince as the best Alpha Male in the end.
Nonetheless, outside her antics and showcases of her ability at work, the whole romantic/emotional part is very frustrating. It makes no sense how these guys all aim for her after all, they don't know anything about her all they see in her(including her real identity) is a tool to use or a place to sink their uselessness and emotional immaturity and whatnot else weakling Men have to show and nothing else.
Sincerely hope the Crown Prince will become a decent human being, cause we all know where this is going.