You have to remember that many Catholic saints lived during times when most people couldn’t read and books were not readily available, and the limited printing resources of the time were more likely to be putting out important books on history, religion or philosophy than some fiction work, so reading novels was not something that one could just nip on down to the bookstore or library and do. Also, a lot of Catholic saints were priests and/or members of religious orders, and as such had extremely limited leisure time for reading for pleasure or doing anything else for pleasure. Finally, when people composed biographies of the saints in past eras, their leisure activities were probably not considered very important, so a saint may well have read some novel but that fact wasn’t considered important by their biographer and wasn’t captured.
Having said that, St. Thomas More probably read novels, as he himself wrote one called Utopia. More was a member of the privileged class in England and wasn’t a priest or religious, which taken all together meant he could read, had the money to acquire books, and the time to read them for enjoyment.
He’s not a saint yet, but Blessed Pier Giorgio Frassati’s favorite book was Dante’s Divine Comedy, which is fiction.
St. Pope John Paul II highly praised Henrik Sienkewicz’s novel Quo Vadis? He also wrote a fictional play called The Jeweler’s Shop.
I’m pretty sure that St. Edith Stein read a few novels during her long life as a student and academic, before she finally entered a convent.
Again not a saint, but Bl. Pope John Paul I’s book Illustrissimi has him giving his views on dozens of authors like Mark Twain and literary characters like Pinocchio. It’s obvious he read a lot of fiction to be able to write the book.
Pope Francis’ favorite book is reportedly a novel, The Betrothed by Alessandro Manzoni.
Please also remember there are a lot of novels that are considered “great Catholic novels” such as Waugh’s Brideshead Revisited, Greene’s The Power and the Glory, and Undset’s Kristin Lavransdatter.
I hope this is helpful. But I also think you need to look at why you feel you need to deny yourself a little pleasurable rest break doing something you enjoy. If the novels you read aren’t containing anything that would lead you personally away from God, then it’s not harmful to spend some time relaxing and enjoying one,
