To help the reader understand multiple characters, you can switch the point of view character throughout the book, using one for each scene.
For example, chapter one is in Karen’s point of view at the party. In the next chapter or scene, we switch to Cissy, the day after the party, hoping Hanson will call her. In the third chapter or scene, we move to Elena, picking up her phone and finding her fiancé Hanson on the line, flirting with some other woman. In the fourth chapter or scene, Karen is woken up with a pounding headache by her cell phone—it is her best friend Elena, who is crying that she thinks her fiancé Hanson is having an affair.
Be judicious in how many point of view characters you use. Too many point of view characters is often confusing for a reader.
For example, in Debbie Macomber’s Blossom Street series, her novels always only have four point of view characters. This helps the reader keep track of who is who, because the reader is dropped into the heads of only four characters out of the larger cast of minor characters.
Typically, a romance will only show two points of view—the hero and heroine. If you choose to use a third point of view character, make sure you have scenes from that character’s point of view throughout the novel, not just a scene or two. It disrupts the flow of the story to make the reader switch to a new point of view character for only a few scenes. Be creative and write the scene from the hero or heroine’s point of view instead.