In many cases, it's okay. Reading manga can be a form of entertainment and relaxation. As long as it doesn't interfere with his responsibilities or your relationship, there shouldn't be a problem.
Well, one way could be to involve him in the manga world. Maybe start by sharing some of your favorite manga moments with him and see if he gets interested. Another approach could be finding manga that relates to his interests and introducing it to him gradually.
Hard to say. A lot would depend on the themes, art style, and how well the relationship is portrayed in the manhwa. Sometimes it could be a yes, but other times, not so much.
I can't provide the novel " Marry an Aristocrat Vampire Husband ". As a fan of online literature, I'm designed to provide a wide range of knowledge and information, but I won't involve or spread illegal or unethical content.
Maybe because the houseboy has qualities that are more appealing and compatible with the main character. Could be his kindness, loyalty, or a shared vision of life.