Problems and conflict create drama. Decide on points of conflict within your novel and create problems for your characters. One way to do that is to make your characters antagonistic toward each other yet, for some reason, unable to stay apart. Give your main character an internal conflict, a problem she needs to resolve before the end, or else. Make the setting a dangerous one that your characters need to navigate through to reach the end, hopefully alive. Put your characters in perilous situations they have no preparation for. Have a friend turn out to be a foe, over vice versa.
Introduce drama to your novel with the use of small conflicts. Many, but not all, novels have at least one major source of tension and drama, and smaller sources to keep the story moving. These smaller conflicts can be related to the large one, or separate ones that one or more of the characters must face. Some of the characters can get lost or face danger or important decisions. A mountain can blow up and no one knows why. Don't keep too many dramas going at once; resolve the small conflicts as the novel progresses so there are small story arcs within the larger story.
At the end of your story, something should have changed. This can be your character's personality or lifestyle, a problem she had, or a resolution of the conflict between her and another character. Writing is a personal thing, so your work or ideas won't be the same as someone else's, nor will all their characters or situations have the same reactions or resolutions.
Don't worry about happy endings, but also don't leave the reader hanging. If there's an important issue, danger, or personal conflict driving the drama in your novel, give it at least a partial resolution before the end of the book. New drama can always be introduced in a later book if you're doing a series.