From what I understand, I think your difficulties with enjoying your current book might be concerning whether you have a "good book" to follow this book with. I don't think you're currently reading series, because knowing what book is next is pretty simple. (For that reason, The Earth's Children series was agonizing: I think the shortest time between books was 10 years) If you have a "TBR pile", it's kind of comforting. If you don't have a physical pile but a list, that's fine too. But, learning how to enjoy your current book without worrying about what to read next is only a decision you can make. And something you'll learn as you go on reading. But, I think mostly a decision. If a worry starts sneaking in, remind yourself, "I have another book to read after this one. It sounds interesting, too" then keep reading. Good luck.