Image from Deposit Photos and filter from Dreamscope
One of the 'secrets' to the romance genre, the well-known secrets, is that there is a happily ever after. That is not true with love stories, which can end happily or tragically. But a romance will get to the point where it all works out for the couple. It's a genre requirement.
What creates the best romances, however, is the belief it might not. He might get killed. She might leave him. They might decide they love each other but cannot work out a life together. That concern is what keeps readers interested, even knowing the end is guaranteed (unless it's a love story). The writer wants the reader to believe there might not be a HEA, which makes for a wonderful feeling when it happens.
One way I try to get that uncertainty into my books is by music. I only listen to music in two settings for my stories-- one is something dangerous, which can be a fight or fast horseback ride. I need an energy that isn't in my daily life and find it in the right music (western soundtracks are great for that).
The other time I need music is for the romantic scenes. Let's face it most writers are not constantly living love stories in their personal lives. We are facing all the normal conflicts that living with someone, raising a family, living in a community bring about. So to write a love scene, I have to get into a mood, and for me, music does it.
More importantly to get into a space where I can make myself believe this couple, in love or not, will not make it. There are certain songs that do that better than others.