Since I'm not acquainted with the 'Secret Love the Bad New Wife' web novel, it's hard to be precise. However, from the title, one can assume that love might be a central theme. The 'bad new wife' aspect could bring in themes like redemption. Maybe the wife is not really bad but has been misunderstood, and the story could be about her journey towards being loved and accepted. Also, the 'secret love' part might involve themes of secrecy, hiding one's true feelings, and the challenges that come with that.
Without having read the 'Secret Love the Bad New Wife' web novel, it's just speculation. But it seems that love and relationships are going to be key themes. The 'bad new wife' might indicate that there are elements of conflict within the relationship. It could also be that the 'secret love' is a result of some sort of social or personal situation that makes it necessary to keep the love hidden. For example, there could be family politics or past events that make the relationship complicated and force the love to be a secret.
I'm sorry, as I haven't read this web novel, I can't say for sure. But based on the title, themes could potentially include forbidden love, as the word 'secret' might imply that the love is not supposed to be out in the open. And the 'bad new wife' part could suggest themes related to difficult relationships or perhaps a character who is initially misjudged.