You should read The Mortal Instruments. I read it after I read TFiOS (I read TFiOS after Allegiant) and it hasn't depressed me yet! Also, you should read If I Stay, I just finished it. It is kind of like TFiOS, but not depressing. If you read TMI series let me know if you like it. If you read If I Stay tell me if you enjoy it. I'm getting ready to read Where She Went, it is the second book for If I Stay. Here's the order of books for TMI;
1 City of Bones 2 City of Ashes 3 City of Glass 4 City of Fallen Angels 5 City of Lost Souls 6 City of Heavenly Fire (will read book 6 soon)