Other things.

Aren't all romance novels the same? If you are asking that, you might be new to this genre.
The main idea around romance fiction is a story built around the development of a romantic relationship. And it can be combined with so many plots and premises. I think that the external conflicts and romantic conflicts work as a team. They add depth to one another.
Plus, sex is fun to write.

I write a dystopian set of romance books. I like to think of the Ice Era Chronicles as a dark romance. I promise you that the end of the books is always happy, but I like the characters to bleed and feel raw and to struggle. I also like my people to be flawed and unattractive. I don't like perfection. 
Because I like writing darker things, I have considered writing Mafia romance or something more with killers.
The In The Mountains books are much lighter. They are fluffy gay romance with softer themes, and I stay away from adding politics to my books. The aliens? I am not sure what subgenre I would put those in, but I don't worry about it. Those are just fun.

I sometimes get asked why I don't write other things, like a mystery or about my time in the military. I don't know what I want to write yet. That's why. But I will get it figured it out one day and may dive into something that isn't a romance, but for now, here we are.
​
Try a romance. It won't bite. Unless it's a vampire book.