Suggest me a book with a psychological aspect

I used to read a ton but I’ve had a lot going on the past few years and haven’t had the chance to read much. I’m looking for a fictional story (doesn’t have to be fantasy) that goes into the psychological aspects of the characters’ actions and the reasons they do what they do. Preferably a romance where the relationship is/was some form of wholesome—I just really want to delve deep into someone’s mind. Thanks in advance for saving my reading career!